Category Archives: ASEAN Climate Outlook Forum

Twenty Fourth Session of the ASEAN Climate Outlook Forum (ASEANCOF-24)

22 – 25 April 2025, MOWRAM Cambodia

Consensus Bulletin for June-July-August (JJA) 2025 Season

The ASEAN Climate Outlook Forum (ASEANCOF) is an avenue to collaboratively develop consensus-based seasonal climate outlooks and related information on a regional scale. The forum’s outlook and its activities contribute significantly to one of the key roles of the ASEAN Specialised Meteorological Centre (ASMC), which is to conduct climate and seasonal prediction for the Association of Southeast Asian Nations (ASEAN) region through pooling the expertise of ASEAN National Meteorological and Hydrological Services (NMHSs). In 2021, the ASEANCOF Working Group was established with the goal to guide and support the long-term development of ASEANCOF, in particular with regard to the implementation of objective outlooks.

The Twenty-Fourth session of ASEANCOF (ASEANCOF-24) was organised by the Ministry of Water Resources and Meteorology, Cambodia (MOWRAM), RIMES, ASMC, the ASEANCOF Working Group, and WMO. A two-day training workshop occurred prior to the COF proper, with training by the UK Met Office, ASMC, and University of Southern Queensland (22 – 23 April).

During the COF proper, participants from the NMHSs of ASEAN Member States created a consensus forecast for the boreal summer monsoon 2025 in the ASEAN region. The consensus for the June-July-August (JJA) 2025 outlook was achieved through a hybrid session, which included presentations from NMHSs, questionnaires, and discussions regarding the current climate conditions and predictions for Southeast Asia. The theme of ASEANCOF-24 was Climate Services and Heat Health. On the last day of ASEANCOF-24, a sharing session was held by the Global Heat Health Information Network (GHHIN) Southeast Asia Hub, followed by a general sharing session by various sector representatives and producers, including UN ESCAP, FAO, and agricultural and health representatives from Lao PDR and Cambodia. A recording of the COF proper is available at https://community.wmo.int/en/meetings/24th-association-southeast-asian-nations-asean-climate-outlook-forum-aseancof-24.

Conditions and Outlook

Recent analysis of sea surface temperature (SST) anomalies over the equatorial Pacific shows average to slightly below-average SSTs across the equatorial Pacific Ocean, and along with atmospheric indicators such as trade wind strength and cloudiness, indicate ENSO-neutral conditions. In the Indian Ocean, the Indian Ocean Dipole (IOD) is neutral.
The international climate outlook predicts that ENSO-neutral conditions will continue into JJA 2025. After JJA 2025, most models predict ENSO-neutral conditions, although there is still a high amount of uncertainty for ENSO predictions issued in April.

The Indian Ocean Dipole (IOD) is also predicted to be neutral during JJA 2025.

The onset of the Southwest monsoon season is predicted to be near average for most of Southeast Asia in 2025, starting from May. The strength of the Southwest monsoon is predicted to be near-average over most of Southeast Asia, based on model predictions.

During JJA 2025, tropical cyclone frequency is predicted to be near average around the Philippine Sea and the South China Sea and above average over the Bay of Bengal.

RAINFALL

For the upcoming boreal (Northern Hemisphere) summer season (JJA 2025):
Above-normal rainfall is predicted over parts of the southern ASEAN region. Near- to above-normal rainfall is predicted over eastern and southern Philippines, parts of east Malaysia, Brunei Darussalam, northeastern Cambodia, and northern and southern Lao PDR.

Below- to near-normal rainfall is predicted over parts of southern Thailand, northwestern Cambodia, coastal central Vietnam and northwestern Philippines.

Elsewhere, near-normal rainfall is predicted.

TEMPERATURE

For the upcoming boreal (Northern Hemisphere) summer season (JJA 2025):
Above-normal temperature is predicted over much of the equatorial region, as well as over eastern and southern Philippines and parts of northern Viet Nam and northwestern Cambodia.

Elsewhere, near- to above-normal¹ temperature is predicted.

¹For this outlook, near-to above-normal temperature corresponds to 50% probability of above-normal temperature, 40% near-normal, and 10% below-normal. Further information is in the consensus maps.

Refer to Annex A for reference on what is meant by “above, near, or below normal” in the outlook. For more information on the boreal (Northern Hemisphere) summer monsoon outlook and further updates on the national scale, the relevant NMHSs should be consulted (see Annex B).

CONSENSUS MAPS FOR JJA 2025

The following maps provide the probabilistic outlooks for JJA 2025 season in terms of tercile categories of “Above Normal” (AN: upper tercile), “Near Normal (NN: middle tercile) and “Below Normal” (BN: lower tercile).

PROBABILISTIC RAINFALL OUTLOOK

PROBABILISTIC TEMPERATURE OUTLOOK

Meeting Documents

ASEANCOF-24 Outlook Bulletin

Acknowledgements

ASEANCOF would like to convey its appreciation to the NMHSs of the ASEAN Member States for sharing their national level forecasts, the Global Producing Centres, the Southeast Asia Regional Climate Centre – Network, RIMES, UN ESCAP, FAO, USQ, GHHIN Southeast Asia Hub and other partners of ASEANCOF for sharing their products and expertise, and the World Meteorological Organization Regional Office in Asia and the Southwest Pacific (WMO-RAP) for their continued support of ASEANCOF. The Forum would also like to thank MOWRAM Cambodia for hosting the forum, with support from RIMES, CREWS and WISER Asia Pacific for the funding support provided for the meeting.

Twenty Third Session of the ASEAN Climate Outlook Forum (ASEANCOF-23)

26-29 November 2024, Online

Consensus Bulletin for December-January-February (DJF) 2024/2025 Season

The ASEAN Climate Outlook Forum (ASEANCOF) is an avenue to collaboratively develop consensus-based seasonal climate outlooks and related information on a regional scale. The forum’s outlook and its activities contribute significantly to one of the key roles of the ASEAN Specialised Meteorological Centre (ASMC), which is to conduct climate and seasonal prediction for the Association of Southeast Asian Nations (ASEAN) region through pooling the expertise of ASEAN National Meteorological and Hydrological Services (NMHSs). In 2021, the ASEANCOF Working Group was established with the goal to guide and support the long-term development of ASEANCOF, in particular with regard to the implementation of objective outlooks.

The Twenty-third session of ASEANCOF (ASEANCOF-23) was organised by the Department of Meteorology and Hydrology of Lao PDR, RIMES, the ASEANCOF Working Group, and WMO. Participants from the NMHSs of ASEAN Member States created a consensus forecast for the boreal winter monsoon 2024/2025 in the ASEAN region. The consensus for the December-January-February (DJF) 2024/2025 outlook was achieved through an online session, which included presentations from ASEAN NMHSs, questionnaires, and discussions regarding the current climate conditions and predictions for Southeast Asia. The theme of ASEANCOF-23 was Agriculture and Climate Services. On the last day of ASEANCOF-23, a sharing session was held which included updates from ASEANCOF-22 around the use of climate services for agriculture.

Conditions and Outlook

Recent analysis of sea surface temperature (SST) anomalies over the equatorial Pacific shows average to slightly below-average SSTs across the equatorial Pacific Ocean, and along with atmospheric indicators such as trade wind strength and cloudiness, indicate La Niña-like conditions. In the Indian Ocean, the positive Indian Ocean Dipole did not develop, and based on the recent analysis, the SST anomalies show signs of a negative Indian Ocean Dipole.
The international climate outlooks predict that a weak La Niña is likely to develop sometime in December 2024 and persist until February 2025. After DJF 2024/2025, most models predict La Niña conditions to transition back to ENSO neutral.
There is a chance that a short-lived negative Indian Ocean Dipole (IOD) may be present during December 2024 based on the model predictions. However, the IOD is predicted to be neutral during January – February 2025.
The onset of the Northeast Monsoon season has been or is expected to be near or later than average for much of the northern ASEAN region. The onset for much of the southern ASEAN region has been or is expected to be near average. The strength of the Northeast Monsoon is predicted to be near average over most of Southeast Asia.
During DJF 2024/2025, tropical cyclone frequency is predicted to be near average around the Philippine Sea, the Bay of Bengal, and South China Sea.

RAINFALL

For the upcoming boreal (Northern Hemisphere) winter season (DJF 2024/2025):
Over the Maritime Continent, near- to above-normal or above-normal rainfall is predicted for much of the region, including the Philippines, Brunei Darussalam, and Singapore. The exception is over parts of the equatorial region, where a mix of near-normal and normal- to below-normal rainfall is predicted.
Across Mainland Southeast Asia, near- to above-normal or above-normal rainfall is predicted for much of the southern part, including southern Myanmar, southern Thailand, Cambodia, southern Lao PDR, and southern Viet Nam. Below-normal rainfall is predicted for northern Viet Nam and elsewhere, near-normal rainfall is predicted.

Below-normal rainfall is predicted over the western part of Northern Philippines. Below- to near- normal rainfall is predicted over southern Lao PDR, the rest of Northern Philippines, and southernmost parts of Southeast Asia. Elsewhere, near-normal rainfall is predicted.¹.

TEMPERATURE

For the upcoming boreal (Northern Hemisphere) winter season (DJF 2024/2025):
Near- to above-normal or above-normal temperature is predicted over most of the ASEAN region. The exception is over northern Lao PDR, and northeast and central Viet Nam, where near-normal temperature is predicted. The highest chance of above-normal temperature is over northern and central Myanmar, northern Thailand, southern Lao PDR, Singapore, the southern Philippines, and Brunei Darussalam.

¹This is based on the climatology period 1991-2020. However, at the national level, Myanmar is using the 1981-2010 climatology as their base period.

Refer to Annex A for reference on what is meant by “above, near, or below normal” in the outlook. For more information on the boreal (Northern Hemisphere) summer monsoon outlook and further updates on the national scale, the relevant NMHSs should be consulted (see Annex B).

Consensus Maps for DJF 2024/2025 Season

The following maps provide the probabilistic outlooks for DJF 2024/2025 season in terms of tercile categories of “Above Normal” (AN: upper tercile), “Near Normal (NN: middle tercile) and “Below Normal” (BN: lower tercile).

PROBABILISTIC RAINFALL OUTLOOK

PROBABILISTIC TEMPERATURE OUTLOOK

Meeting Documents

ASEANCOF-23 Outlook Bulletin

Acknowledgements

ASEANCOF would like to convey its appreciation to the NMHSs of the ASEAN Member States for sharing their national level forecasts, the Global Producing Centres, the Southeast Asia Regional Climate Centre – Network, RIMES, UN ESCAP, and other partners of ASEANCOF for sharing their products and expertise, and the World Meteorological Organization Regional Office in Asia and the Southwest Pacific (WMO-RAP) for their continued support of ASEANCOF. The Forum would also like to thank DMH Lao PDR for hosting the forum virtually, as well as trainers from RIMES and UK Met Office.

Twenty Second Session of the ASEAN Climate Outlook Forum (ASEANCOF-22)

27-30 May 2024, DMH Lao PDR

Consensus Bulletin for June-July-August (JJA) 2024 Season

The ASEAN Climate Outlook Forum (ASEANCOF) is an avenue to collaboratively develop consensus-based seasonal climate outlooks and related information on a regional scale. The forum’s outlook and its activities contribute significantly to one of the key roles of the ASEAN Specialised Meteorological Centre (ASMC), which is to conduct climate and seasonal prediction for the Association of Southeast Asian Nations (ASEAN) region through pooling the expertise of ASEAN National Meteorological and Hydrological Services (NMHSs). In 2021, the ASEANCOF Working Group was established with the goal to guide and support the long-term development of ASEANCOF, in particular with regard to the implementation of objective outlooks.

The Twenty-Second session of ASEANCOF (ASEANCOF-22) was organised by the Department of Meteorology and Hydrology of Lao PDR, RIMES, the ASEANCOF Working Group, and WMO. Participants from the NMHSs of ASEAN Member States created a consensus forecast for the boreal summer monsoon 2024 in the ASEAN region. The consensus for the June-July-August (JJA) 2024 outlook was achieved through a hybrid session, which included presentations from different NMHSs, questionnaires, and discussions regarding the current climate conditions and predictions for Southeast Asia. There was also two-day pre-COF training, conducted by the UK Met Office under the WISER Asia Pacific project and RIMES. The theme of ASEANCOF-22 was Agriculture and Climate Services, with a focus on drought. On the last day of ASEANCOF-22, a sharing session was held which included presentations from UN ESCAP, FAO, and WFP, as well as discussion on ways to improve ASEANCOF.

Conditions and Outlook

Recent analysis of sea surface temperature (SST) anomalies over the equatorial Pacific shows average to slightly below-average SSTs across the equatorial Pacific Ocean, and along with atmospheric indicators such as trade wind strength and cloudiness, indicate ENSO-neutral conditions. In the Indian Ocean, the Indian Ocean Dipole is also neutral.

The international climate outlook predicts that a La Niña is likely to develop sometime during JJA 2024. After JJA 2024, most models predict La Niña conditions to continue until the end of the year.
There is a chance that a weak positive Indian Ocean Dipole (IOD) may become established during JJA 2024 based on the model predictions. However, it is predicted to most likely be short-lived.

The onset of the Southwest monsoon season has been or is expected to be near average for much of Mainland Southeast Asia, apart from Thailand where the onset is later than average. The onset of the Southwest monsoon for much of the Maritime Continent has been or is expected to be near average. The strength of the Southwest monsoon is predicted to be near average over most of the Southeast Asia, based on model predictions.

During JJA 2024, tropical cyclone frequency is predicted to be below average around the Philippine Sea and the Bay of Bengal, and near average around South China Sea.

Taking into consideration the national level forecasts, the present state of the climate, and the forecasts available from the GPCs, ASEANCOF-22 agreed on the following consensus-based outlook for JJA 2024 over the ASEAN region:

RAINFALL

Above-normal rainfall is predicted over northern Myanmar, parts of Cambodia and parts of the equatorial region, including Brunei Darussalam and middle part of East Malaysia. Near- to above-normal rainfall is predicted over southern Thailand, western part of East Malaysia, and the southern Philippines, as well as parts of Mainland Southeast Asia including western Myanmar, northwestern Lao PDR, parts of Cambodia, and southern Viet Nam.

Below-normal rainfall is predicted over the western part of Northern Philippines. Below- to near- normal rainfall is predicted over southern Lao PDR, the rest of Northern Philippines, and southernmost parts of Southeast Asia. Elsewhere, near-normal rainfall is predicted.¹.

TEMPERATURE

Above normal temperature is predicted over most of Southeast Asia, apart from over much of Myanmar, Lao PDR, Cambodia, Brunei Darussalam, and the Philippines where near- to above-normal temperature is predicted.

¹This is based on the climatology period 1991-2020. However, at the national level, Myanmar is using the 1981-2010 climatology as their base period.

Refer to Annex A for reference on what is meant by “above, near, or below normal” in the outlook. For more information on the boreal (Northern Hemisphere) summer monsoon outlook and further updates on the national scale, the relevant NMHSs should be consulted (see Annex B).

Consensus Maps for JJA 2024 Season

The following maps provide the probabilistic outlooks for JJA 2024 season in terms of tercile categories of “Above Normal” (AN: upper tercile), “Near Normal (NN: middle tercile) and “Below Normal” (BN: lower tercile).

PROBABILISTIC RAINFALL OUTLOOK

PROBABILISTIC TEMPERATURE OUTLOOK

Meeting Documents

ASEANCOF-22 Outlook Bulletin

Acknowledgements

ASEANCOF would like to convey its appreciation to the NMHSs of the ASEAN Member States for sharing their national level forecasts, the Global Producing Centres, the Southeast Asia Regional Climate Centre – Network, RIMES, UN ESCAP, FAO, WFP, and other partners of ASEANCOF for sharing their products and expertise, and the World Meteorological Organization Regional Office in Asia and the Southwest Pacific (WMO-RAP) for their continued support of ASEANCOF. The Forum would also like to thank DMH Lao PDR for hosting the forum, with support from RIMES, and CREWS Cambodia and Lao PDR and WISER Asia Pacific for the funding support provided for the meeting.

Twentieth Session of the ASEAN Climate Outlook Forum (ASEANCOF-21)

17, 20, 21, 23 Nov 2023, MSS

Consensus Bulletin for December-January-February (DJF) 2023-2024 Season

The ASEAN Climate Outlook Forum (ASEANCOF) is an avenue to collaboratively develop consensus-based seasonal climate outlooks and related information on a regional scale. The forum’s outlook and its activities contribute significantly to one of the key roles of the ASEAN Specialised Meteorological Centre (ASMC), which is to conduct climate and seasonal prediction for the Association of Southeast Asian Nations (ASEAN) region through pooling the expertise of ASEAN National Meteorological and Hydrological Services (NMHSs). In 2021, the ASEANCOF Working Group was established with the goal to guide and support the long-term development of ASEANCOF, in particular with regard to the implementation of objective outlooks.

The Twenty-First session of ASEANCOF (ASEANCOF-21) was organised by Meteorological Service Singapore (MSS) in collaboration with ASMC and the ASEANCOF Working Group. ASEANCOF-21 marked 10 years since the first ASEANCOF was held in December 2013. Participants from the NMHSs of ASEAN Member States created a consensus forecast for the boreal winter monsoon 2023/2024 in the ASEAN region. The consensus for the December-January-February (DJF) 2023/2024 outlook was achieved through an online session, which included presentations from different NMHSs, questionnaires, and discussions regarding the current climate conditions and predictions for Southeast Asia. The theme of ASEANCOF-21 was ‘The Future of Climate Services in Southeast Asia’’. On the last day of ASEANCOF-21, a sharing session was held which included presentations on the review of 10 years of ASEANCOF, Pilot Hydrological Outlook Forum, and WISER Asia Pacific project.

Conditions and Outlook

Recent analysis of sea surface temperature (SST) anomalies over the equatorial Pacific shows well above-average SSTs over the Nino3.4 region, along with atmospheric indicators such as trade wind strength and cloudiness, indicating El Niño conditions. In the Indian Ocean, a positive Indian Ocean Dipole is present.

For DJF 2023/2024, the current El Niño conditions are likely to continue. After DJF 2023/2024, global climate models predict the El Niño conditions to gradually weaken, though continue to indicate El Niño conditions for much of the first half of 2024. The peak strength of the ongoing El Niño, based on Nino3.4 index, is predicted to be moderate to strong.

The positive IOD is predicted to weaken and return to IOD-neutral over DJF 2023/2024.

The onset of the Northeast monsoon season has been or is expected to be later than average for much of Mainland Southeast Asia, with near or later than average over some parts of the Maritime Continent. The strength of the Northeast monsoon is expected to be weaker than normal over most of the Southeast Asia, based on model predictions and supported by the ongoing El Niño conditions.

During DJF 2023/2024, tropical cyclone frequency is predicted to be below average around the Philippine Sea and the Bay of Bengal, and below to near average around South China Sea.

Taking into consideration the national level forecasts, the present state of the climate, and the forecasts available from the GPCs, ASEANCOF-21 agreed on the following consensus-based outlook for DJF 2023-24 over the ASEAN region:

RAINFALL

Over much of the Maritime Continent, below- to near-normal rainfall is predicted, apart from over the equatorial region, where a mix of below- to above-normal rainfall is predicted.

For Mainland Southeast Asia, a mix of near- to above-normal rainfall is predicted. Near- to above-normal rainfall is predicted over parts of northern and central Mainland Southeast Asia, while below- to near-normal rainfall is predicted mainly over western parts. Elsewhere over this region, near-normal rainfall is predicted.

TEMPERATURE

Near- to above-normal temperature is predicted over Southeast Asia. While above-normal temperature is predicted for most of the region, near-normal temperature is predicted over parts of northern and western Myanmar, and near- to above-normal temperature is predicted over parts of Lao PDR, Viet Nam, and the Philippines.

Refer to Annex A for reference on what is meant by “above, near, or below normal” in the outlook. For more information on the boreal (Northern Hemisphere) summer monsoon outlook and further updates on the national scale, the relevant NMHSs should be consulted (see Annex C).

Consensus Maps for DJF 2023/2024 Season

The following maps provide the probabilistic outlooks for DJF 2023/2024 season in terms of tercile categories of “Above Normal” (AN: upper tercile), “Near Normal (NN: middle tercile) and “Below Normal” (BN: lower tercile).

PROBABILISTIC RAINFALL OUTLOOK

PROBABILISTIC TEMPERATURE OUTLOOK

Meeting Documents

ASEANCOF-21 Outlook Bulletin

Acknowledgements

ASEANCOF would like to convey its appreciation to the NMHSs of the ASEAN Member States for sharing their national level forecasts, the GPCs, the Southeast Asia Regional Climate Centre – Network, RIMES, UN ESCAP, and other partners of ASEANCOF for sharing their products and expertise, and the World Meteorological Organization Regional Office in Asia and the Southwest Pacific (WMO-RAP) for their continued support of ASEANCOF.

Twentieth Session of the ASEAN Climate Outlook Forum (ASEANCOF-20)

25, 26, 30 May 2023, ASMC

Consensus Bulletin for June-July-August (JJA) 2023 Season

The ASEAN Climate Outlook Forum (ASEANCOF) is an avenue to collaboratively develop consensus-based seasonal climate outlooks and related information on a regional scale. The forum’s outlook and its activities contribute significantly to one of the key roles of the ASEAN Specialised Meteorological Centre (ASMC), which is to conduct climate and seasonal prediction for the Association of Southeast Asian Nations (ASEAN) region through pooling the expertise of ASEAN National Meteorological and Hydrological Services (NMHSs). In 2021, the ASEANCOF Working Group was established with the goal to guide and support the long-term development of ASEANCOF, in particular with regard to the implementation of objective outlooks.

The Twentieth session of ASEANCOF (ASEANCOF-20) was organised by ASMC and the ASEANCOF Working Group. Participants from the NMHSs of ASEAN Member States created a consensus forecast for the boreal summer monsoon 2023 in the ASEAN region. The consensus for the June-July-August (JJA) 2023 outlook was achieved through an online session, which included presentations from different NMHSs, questionnaires, and discussions regarding the current climate conditions and predictions for Southeast Asia. In particular, ASEANCOF considered the influence of the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on the climate system over Southeast Asia. The theme of ASEANCOF-20 was ‘Advances in climate services on subseasonal to seasonal timescales’. On the last day of ASEANCOF-20, a sharing session was held on the impact of El Niño on Southeast Asia, involving NMHSs and users of ASEANCOF information.

Conditions and Outlook

Recent analysis of sea surface temperature (SST) anomalies over the equatorial Pacific shows average to slightly above-average SSTs across most of the equatorial Pacific Ocean, and along with atmospheric indicators such as trade wind strength and cloudiness, indicate ENSO-neutral conditions. In the Indian Ocean, the Indian Ocean Dipole (IOD) is also neutral.

An El Niño is highly likely to become established during JJA 2023. After JJA 2023, most global climate models predict the El Niño conditions to continue until the end of the year. The strength of the upcoming El Niño is uncertain, although some models are predicting that it could be moderate to strong.

A positive IOD is predicted to become establish during JJA 2023. Most models predict the IOD to return to neutral before the end of 2023.

The onset of the Southwest monsoon season has been or is expected to be later than average for much of Mainland Southeast Asia, while near average for the rest of the region. Over western parts of the region, the strength of the Southwest monsoon is expected to be stronger than average, with weaker than average or near average strength for the rest of the region, based on model predictions and supported by the predicted El Niño conditions.

During JJA 2023, tropical cyclone frequency is predicted to be below to near average around the South China Sea and the Philippine Sea and near average around the Bay of Bengal.

Taking into consideration the national level forecasts, the present state of the climate, and the forecasts available from the GPCs, ASEANCOF-20 agreed on the following consensus-based outlook for JJA 2023 over the ASEAN region:

RAINFALL

Over most of the southern ASEAN region, below- to near-normal rainfall is predicted. The exceptions include northeastern Borneo and eastern Maritime Continent where near- to above-normal rainfall is predicted.

Over much of the northern ASEAN region, a mix of near- to above-normal rainfall is predicted. Above-normal rainfall is predicted over parts of southwestern and southeastern Mainland Southeast Asia, while near- to above-normal rainfall is predicted elsewhere over this region. Above-normal rainfall is predicted for much of the western half of the Philippines, with near- to above-normal rainfall elsewhere¹.

TEMPERATURE

Near- to above-normal temperature is predicted over Southeast Asia¹. Near-normal temperature is predicted over parts of the southern Maritime Continent, including southern Sumatra and Java. Near- to above-normal temperature is predicted over the southwestern and southeastern parts of Mainland Southeast Asia, Malaysia, and the Philippines. Elsewhere in Southeast Asia, above-normal temperature is predicted.

¹This is based on the climatology period 1991-2020. However, at the national level, Myanmar is using the 1981-2010 climatology as their base period.

Refer to Annex A for reference on what is meant by “above, near, or below normal” in the outlook. For more information on the boreal (Northern Hemisphere) summer monsoon outlook and further updates on the national scale, the relevant NMHSs should be consulted (see Annex B).

Consensus Maps for JJA 2023 Season

The following maps provide the probabilistic outlooks for JJA 2023 season in terms of tercile categories of “Above Normal” (AN: upper tercile), “Near Normal (NN: middle tercile) and “Below Normal” (BN: lower tercile).

PROBABILISTIC RAINFALL OUTLOOK

PROBABILISTIC TEMPERATURE OUTLOOK

Meeting Documents

ASEANCOF-20 Outlook Bulletin

Acknowledgements

ASEANCOF would like to convey its appreciation to the NMHSs of the ASEAN Member States for sharing their national level forecasts, the GPCs, the Southeast Asia Regional Climate Centre – Network, RIMES, UN ESCAP, and other partners of ASEANCOF for sharing their products and expertise, and the World Meteorological Organization Regional Office in Asia and the Southwest Pacific (WMO-RAP) for their continued support of ASEANCOF.

Nineteenth Session of the ASEAN Climate Outlook Forum (ASEANCOF-19)

21 to 25 Nov 2022, MSS

Consensus Bulletin for December-January-February (DJF) 2022/2023 Season

The ASEAN Climate Outlook Forum (ASEANCOF) is an avenue to collaboratively develop consensus-based seasonal climate outlooks and related information on a regional scale. The forum’s outlook and its activities contribute significantly to one of the key roles of the ASEAN Specialised Meteorological Centre (ASMC), which is to conduct climate and seasonal prediction for the Association of Southeast Asian Nations (ASEAN) region through pooling the expertise of ASEAN National Meteorological and Hydrological Services (NMHSs). In 2021, the ASEANCOF Working Group was established with the goal to guide and support the long-term development of ASEANCOF, in particular with regard to the implementation of objective outlooks.

The Nineteenth session of ASEANCOF (ASEANCOF-19) was organised by Meteorological Service Singapore (MSS) in collaboration with ASMC and the ASEANCOF Working Group. Participants from the NMHSs of ASEAN Member States created a consensus forecast for the boreal winter monsoon 2022-2023 in the ASEAN region. The consensus for the December-January-February (DJF) 2022-2023 outlook was achieved through an online session, which included presentations from different Global Producing Centres (GPCs), NMHSs, questionnaires, and discussions regarding the current climate conditions and predictions for Southeast Asia. In particular, ASEANCOF considered the influence of the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on the climate system over Southeast Asia. The theme of ASEANCOF-19 was climate services for agriculture. On the last day of ASEANCOF-19, a webinar was held involving both producers and users of seasonal outlooks, including presentations on using climate services for agriculture.

Conditions and Outlook

Recent analysis of sea surface temperature (SST) anomalies over the equatorial Pacific shows below-average SSTs across the central and eastern equatorial Pacific Ocean indicative of La Niña.

The international climate outlook predicts that the La Niña is likely to weaken during DJF 2022/2023, although overall still indicates La Niña conditions. After DJF 2022/2023, most models predict the ENSO state to gradually return to neutral.

While a negative Indian Ocean Dipole (IOD) was present for much of the second half of 2022, models predict the IOD to return to neutral by the end of 2022.

The onset of the Northeast monsoon season has been or is expected to be near average in many parts of the region. Over much of Southeast Asia, the strength of the Northeast monsoon is expected to be near average or stronger than average, based on model predictions and supported by the La Niña conditions.

Overall, the tropical cyclone frequency is expected to be near average in the Bay of Bengal and around the South China Sea and the Philippine Sea.

Taking into consideration the national level forecasts, the present state of the climate, and the forecasts available from the GPCs, ASEANCOF-19 agreed on the following consensus-based outlook for DJF 2022/2023 over the ASEAN region:

RAINFALL

Over the Maritime Continent, a mix of below to above normal rainfall is predicted. In particular, near to above normal rainfall is most likely over much of the Philippines and Brunei Darussalam, while near normal rainfall is most likely over much of Malaysia and Singapore.

Over Mainland Southeast Asia, below normal rainfall is most likely over northern parts, including northern Myanmar as well as northern Viet Nam. Above normal rainfall is most likely over southern and southeastern Mainland Southeast Asia, including southern Thailand, parts of Cambodia, and southern Viet Nam. Elsewhere, near normal rainfall is predicted.¹

¹This is based on the climatology period 1991-2020. However, at the national level, Myanmar is using the 1981-2010 climatology as their base period.

TEMPERATURE

Over the ASEAN region, a mix of below- to above-normal temperature is predicted. Above normal temperature is most likely over parts of Myanmar, northwestern Viet Nam and the eastern Maritime Continent, while below to near normal temperature is most likely over southeastern Mainland Southeast Asia. Elsewhere, near or near to above normal temperature is predicted.²

²This is based on the climatology period 1991-2020. However, at the national level, Myanmar is using the 1981-2010 climatology as their base period.

Refer to Annex A for reference on what is meant by “above, near, or below normal” in the outlook. For more information on the boreal (Northern Hemisphere) summer monsoon outlook and further updates on the national scale, the relevant NMHSs should be consulted (see Annex B).

Consensus Maps for DJF 2022/2023 Season

The following maps provide the probabilistic outlooks for DJF 2022/2023 season in terms of tercile categories of “Above Normal” (AN: upper tercile), “Near Normal (NN: middle tercile) and “Below Normal” (BN: lower tercile).

PROBABILISTIC RAINFALL OUTLOOK

PROBABILISTIC TEMPERATURE OUTLOOK

Meeting Documents

ASEANCOF-19 Outlook Bulletin

Acknowledgements

ASEANCOF would like to convey its appreciation to the NMHSs of the ASEAN Member States for sharing their national level forecasts, the GPCs, the Southeast Asia Regional Climate Centre – Network, RIMES, UN ESCAP, and other partners of ASEANCOF for sharing their products and expertise, and the World Meteorological Organization Regional Office in Asia and the Southwest Pacific (WMO-RAP) for their continued support of ASEANCOF.

Eighteenth Session of the ASEAN Climate Outlook Forum (ASEANCOF-18)

24 and 26 May 2022, PAGASA
 

Consensus Bulletin for June-July-August (JJA) 2022 Season

The ASEAN Climate Outlook Forum (ASEANCOF) is an avenue to collaboratively develop consensus-based seasonal climate outlooks and related information on a regional scale. The forum’s outlook and its activities contribute significantly to one of the key roles of the ASEAN Specialised Meteorological Centre (ASMC), which is to conduct climate and seasonal prediction for the Association of Southeast Asian Nations (ASEAN) region through pooling the expertise of ASEAN National Meteorological and Hydrological Services (NMHSs). In 2021, the ASEANCOF Working Group was established with the goal to guide and support the long-term development of ASEANCOF, in particular with regard to the implementation of objective outlooks.
 
The Eighteenth session of ASEANCOF (ASEANCOF-18) was organised by the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) in collaboration with the ASMC and the ASEANCOF Working Group. Participants from the NMHSs of ASEAN Member States created a consensus forecast for the boreal summer monsoon 2022 in the ASEAN region. The consensus for June-July-August (JJA) 2022 outlook was achieved through an online session, which included presentations from different NMHSs, questionnaires, and discussions regarding the current climate conditions and predictions in the Southeast Asia region. In particular, ASEANCOF considered the influence of the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on the climate system over Southeast Asia. There was also a special focus on monsoon variability, with a presentation from the Regional Working Group on Asian-Australian Monsoon (AAM-WG).

Conditions and Outlook

Recent analyses of sea surface temperature (SST) anomalies over the equatorial Pacific show below average SSTs across the central and eastern tropical Pacific Ocean indicative of La Niña. The international climate outlooks predict that the La Niña is likely to weaken during JJA 2022, although still overall indicate La Niña conditions. After JJA 2022, most models predict the ENSO state to be either cool ENSO neutral or La Niña.

The current IOD state is neutral. Most models predict a negative IOD developing during JJA 2022, with some models predicting the said negative IOD to be strong.

The onset of the Southwest Monsoon season has been earlier than normal in many parts of Mainland Southeast Asia, and near normal in the Maritime Continent. Over much of Southeast Asia, the strength of the Southwest Monsoon is expected to be near normal or weaker than normal, based on model predictions.

Overall, the tropical cyclone frequency is expected to be near average in the Bay of Bengal, while below to near average around the South China Sea and in the Philippine Sea. As there is an expected weakening of La Niña in JJA 2022, no significant deviation from the climatology of tropical cyclone frequency is expected during the forecast period.

Taking into consideration the national level forecasts, the present state of the climate, and the forecasts available from the global prediction centres (GPCs), the ASEANCOF-18 agreed on the following consensus-based outlook for JJA 2022 in the ASEAN region:

RAINFALL

Over much of the southern ASEAN region, near to above normal rainfall is predicted. Near to above normal rainfall is predicted over Brunei Darussalam and many parts of Malaysia, with above normal rainfall predicted most elsewhere. The exceptions include parts of the western and eastern Maritime Continent, where near to below normal rainfall is predicted.

Over much of the northern ASEAN region, a mix of below to above normal rainfall is predicted. Near to below normal rainfall is predicted over the western and southeast portion of Mainland Southeast Asia, and northwest Philippines. Near to above normal rainfall is predicted over portions of northeast and southern Mainland Southeast Asia, and southern Philippines. Elsewhere in the northern ASEAN region, near normal rainfall is predicted.

TEMPERATURE

Near to above normal temperature is predicted over the ASEAN region. The highest likelihood of above normal temperature is over the southern Maritime Continent and Lao PDR, while near normal temperature is predicted over northern Myanmar, northern and central Viet Nam, and parts of the western Maritime Continent. An equal chance of near to above normal temperature is predicted over southern Myanmar, Thailand, Cambodia, southern Viet Nam, the Philippines, Malaysia, and Brunei Darussalam.

Refer to Annex A for reference on what is meant by “above, near, or below normal” in the outlook. For more information on the boreal (Northern Hemisphere) summer monsoon outlook and further updates on the national scale, the relevant NMHSs should be consulted (see Annex B).
 

Consensus Maps for JJA 2022 Season

The following maps provide the probabilistic outlooks for JJA 2022 season in terms of tercile categories of “Above Normal” (AN: upper tercile), “Near Normal (NN: middle tercile) and “Below Normal” (BN: lower tercile).
 

PROBABILISTIC RAINFALL OUTLOOK

PROBABILISTIC TEMPERATURE OUTLOOK

Meeting Documents

ASEANCOF-18 Outlook Bulletin
 

Acknowledgements

ASEANCOF would like to convey its appreciation to the NMHSs of the ASEAN Member States for sharing their national level forecasts, the GPCs, the Southeast Asia Regional Climate Centre – Network, and other partners of ASEANCOF for sharing their products and expertise, and the World Meteorological Organization Regional Office in Asia and the Southwest Pacific (WMO-RAP) for their continued support of ASEANCOF.