Category Archives: Haze Review

Review of Regional Haze Situation for August 2023

1.1 In August 2023, the southwest monsoon conditions continued as the prevailing winds blew from the southwest or west over the northern ASEAN region and blew from the southeast or southwest over the southern ASEAN region (Figure 1). The southwesterly winds over the northern parts of the Philippines were strong at times under the influence of Super Typhoon Saola towards the end of the month.

1.2 As the monsoon rainband moved further north of the Equator, it was dry on most days of the month over Java, the Lesser Sunda Islands, Sulawesi and the southern parts of Sumatra and Kalimantan. Showers were observed over the rest of the ASEAN region on most days. In particular, Super Typhoon Saola brought intense and widespread rainfall over the northern parts of the Philippines (Figure 1).

Figure 1: Average Daily Rainfall and Mean Winds for August 2023. (Source: JAXA GsMaP and GFS, respectively)

1.3 Compared to July 2023, there was a significant increase in the number of hotspots over the southern ASEAN region in August 2023 with the highest increase in hotspot activity observed over Kalimantan. Year-on-year comparison (Figure 2) also shows higher hotspot counts in Kalimantan compared to the past 3 years and were comparable to the hotspot count in 2019. In the rest of the ASEAN region, the overall hotspot counts were lower or comparable to previous years.

Figure 2: Hotspot counts for the southern ASEAN region for August (2019-2023) based on NOAA-20 satellite surveillance.

Figure 3: Hotspot counts for the northern ASEAN region for August (2019-2023) based on NOAA-20 satellite surveillance.

1.4 Under the prolonged dry conditions, clusters of hotspots were detected in Kalimantan (Figure 4) with more intense and persistent hotspots located mostly in South and West Kalimantan (Figure 4 and 5). Isolated hotspots were also detected mainly in Java, the Lesser Sunda Islands, Sulawesi and the southern and central parts of Sumatra (Figure 4). Moderate smoke haze was observed on some days in Kalimantan as well as in the southern and central parts of Sumatra (Figure 9). The smoke haze situation over South and West Kalimantan escalated towards the end of the month with dense smoke haze observed on some days (Figure 6 and 8). The smoke haze over West Kalimantan was also observed to drift northwards into western Sarawak on a few occasions (Figure 6 and 7). In the northern ASEAN region, the hotspot activity remained low under the prevailing wet weather with isolated hotspots mostly detected in Viet Nam (Figure 4).

Figure 4: Distribution of hotspots detected in August 2023 based on NOAA-20 satellite surveillance.

Figure 5: Maximum fire intensity in August 2023 based on NOAA-20 satellite surveillance.

Figure 6: Number of days with moderate to dense haze observed in August 2023 based on NOAA-20 satellite surveillance.

Figure 7: Slight to moderate smoke haze was observed in West Kalimantan drifting northwards towards western Sarawak on 31 August 2023. (Source: Himawari-9 satellite)

Figure 8: Moderate to dense smoke haze were observed over South Kalimantan on 31 August 2023. (Source: Himawari-9 satellite)

Figure 9: Moderate smoke plumes were observed to emanate from hotspots detected in the southern parts of Sumatra on 31 August 2023. (Source: Himawari-9 satellite)

Review of Regional Haze Situation for July 2023

1.1 Southwest Monsoon conditions persisted in July 2023, with the monsoon rainband located predominantly over the northern ASEAN region. The prevailing winds over areas north of the equator blew mainly from the southeast or southwest, while the prevailing winds over areas south of the equator blew mostly from the east or southeast (Figure 1). Typhoon Talim (Figure 9) and Super Typhoon Doksuri (Figure 10) brought about periods of strong winds over the northern half of the equator.

1.2 Over the southern ASEAN region, brief periods of dry weather conditions were observed for most of July 2023. Towards the end of the month, dry conditions persisted over Kalimantan with clusters of scattered hotspots and slight to moderate smoke haze observed over the western and southeastern parts of Kalimantan. On some days, smoke haze emanating from clusters of hotspots in West Kalimantan was observed to drift northwards into western Sarawak. On 28 July 2023, Alert Level 2 was activated for Kalimantan as hotspot counts were persistently high and there was an increasing risk of transboundary haze. Over the northern ASEAN region, wet weather was observed on most days during the month, subduing the overall haze situation in the region. High rainfall amounts were recorded over the northern parts of the Philippines due to Typhoon Talim which made landfall over the Philippines on July 13, 2023 and Super Typhoon Doksuri which passed the northern tip of the Philippines between July 25 and July 27, 2023.

Figure 1: Average Daily Rainfall and Mean Winds for July 2023. (Source: JAXA GsMaP and GFS, respectively)

1.3 Over the southern ASEAN region, there was a rise in overall hotspot activity due to periods of drier conditions, with the hotspot counts in the region higher or comparable to previous years (Figure 2). Notably, Kalimantan experienced the most significant rise in hotspot activity, with the highest count recorded in five years. Over the Mekong sub-region, the overall hotspot count in 2023 was mostly comparable to or lower than in previous years (Figure 3).

Figure 2: Hotspot counts for the southern ASEAN region for July (2019-2023) based on NOAA-20 satellite surveillance.

Figure 3: Hotspot counts for the northern ASEAN region for July (2019-2023) based on NOAA-20 satellite surveillance.

1.4 Towards the end of July 2023, hotspot activities were persistent in West and South Kalimantan, as well as parts of the Lesser Sunda Islands (Figure 4). The overall fire intensity for the ASEAN region was low, except for over parts of western Kalimantan where moderate fire intensity was detected (Figure 5). Slight to moderate smoke haze was observed over the western and southeastern parts of Kalimantan (Figures 6, 7 and 8).

Figure 4: Distribution of hotspots detected in July 2023 based on NOAA-20 satellite surveillance.

Figure 5: Maximum fire intensity in July 2023 based on NOAA-20 satellite surveillance.

Figure Figure 6: Number of days with moderate to dense haze observed in July 2023 based on NOAA-20 satellite surveillance.

Figure 7: Slight to moderate smoke haze was observed in West Kalimantan drifting northwards towards Sarawak on 27 July 2023. (Source: Himawari-9 satellite surveillance)

Figure 8: Moderate smoke plumes were observed to emit from the hotspots detected in South Kalimantan on 29 July 2023. (Source: NOAA-20 satellite surveillance)

Figure 9: Typhoon Talim over the western Pacific Ocean (Source: MODIS satellite surveillance)

Figure 10: Super Typhoon Doksuri over the western Pacific Ocean (Source: NOAA-20 satellite surveillance)

Review of Regional Haze Situation for June 2023

1.1 Southwest Monsoon conditions were fully established in June 2023, with the passage of the monsoon rainband north of the Equator. The prevailing winds over areas north of the equator blew mainly from the southeast or southwest, while the prevailing winds blew mostly from the east or southeast (Figure 1).

1.2 Brief periods of dry weather conditions were observed over parts of southern Sumatra, southern Kalimantan, Java, and the Lesser Sunda Islands. Elsewhere in the ASEAN region, shower activities were observed on most days during the month (Figure 1).

Figure 1: Average Daily Rainfall and Mean Winds for June 2023. (Source: JAXA GsMaP and GFS, respectively)

1.3 There was an increase in overall hotspot activity in June 2023 over the southern ASEAN region due to brief periods of dry conditions, with the hotspot counts in the region higher or comparable to previous years (Figure 2). In particular, the highest hotspot activity was detected in Sumatra, and the hotspot counts for both Sumatra and Kalimantan were the highest in 5 years. Over the Mekong sub-region, the overall hotspot count was mostly lower than in previous years (Figure 3).

Figure 2: Hotspot counts for the southern ASEAN region for June (2019-2023) based on NOAA-20 satellite surveillance.

Figure 3: Hotspot counts for the northern ASEAN region for June (2019-2023) based on NOAA-20 satellite surveillance.

1.4 Hotspot activities were more persistent in parts of western and central Sumatra, as well as West Kalimantan during the review period of June 2023. Localised smoke plumes were also observed to emanate from a few hotspots in Sumatra and Kalimantan on some days (Figures 6 and 7). However, the overall fire intensity has generally remained low.

Figure 4: Distribution of hotspots detected in June 2023 based on NOAA-20 satellite surveillance.

Figure 5: Maximum fire intensity in June 2023 based on NOAA-20 satellite surveillance.

Figure 6: Localised smoke plumes moving in the north-northwest direction were observed in central Sumatra on 20 June 2023. (Source: Himawari-9 satellite surveillance)

Figure 7: A localised smoke plume moving in the northeast direction was observed to emanate from a hotspot in western Kalimantan on 26 June 2023. (Source: NOAA-20 satellite surveillance)

Review of Regional Haze Situation for May 2023

1.1 Inter-monsoon conditions prevailed over the ASEAN region in May 2023 and the wind conditions were light and variable in direction on most days (Figure 1). Two tropical cyclones affected parts of the region in May 2023, namely Tropical Cyclone Mocha over Bay of Bengal (Figure 2) and Super Typhoon Mawar over the western Pacific Ocean (Figure 3). The storms brought brief periods of widespread rainfall and strong winds over Myanmar and the Philippines, respectively. According to the Joint Typhoon Warning Centre (JTWC), Super Typhoon Mawar was the strongest Northern Hemisphere tropical cyclone ever recorded in the month of May. By the end of May 2023, the inter-monsoon period had gradually transitioned into the Southwest Monsoon for most parts of the ASEAN region.

1.2 Over the northern ASEAN region, dry conditions continued over much of the Mekong sub-region in early May 2023. Elevated hotspot activity persisted in many parts of the sub-region, particularly in Lao PDR and Myanmar (Figure 4). On many days, isolated to scattered hotspots were detected in northern and western parts of the sub-region, where moderate to dense smoke haze, occasionally transboundary, was observed (Figure 6 – 9). Following the return of showers from the second week of May 2023, hotspot activity over the Mekong sub-region had steadily decreased. The ASMC Alert Level for the sub-region was downgraded to Alert Level 1 on 9 May 2023, and subsequently the end of dry season for the sub-region was declared on 24 May 2023.

1.3 For the southern ASEAN region, the weather was rainy and cloudy for most of May 2023. However, periods of drier conditions began to set in over some parts of the region from last week of the month, as monsoon rain band shifted further north from the Equator. Few to isolated hotspots, some with localised smoke plumes, were observed in the fire-prone areas of Sumatra, Kalimantan, and Peninsular Malaysia. A slight increase in hotspot activity was also detected, following the gradual onset of Southwest Monsoon conditions (Figure 5). On 29 May 2023, ASMC activated Alert Level 1 for the southern ASEAN region, signaling the start of the traditional dry season.

Figure 1: Average Daily Rainfall and Mean Winds for May 2023. (Source: JAXA GsMaP and GFS, respectively)

Figure 2: Tropical Cyclone Mocha over the Bay of Bengal and made landfall over Myanmar on 15 May 2023. (Source: Himawari-9 satellite surveillance)

Figure 3: Super Typhoon Mawar over the western Pacific Ocean brought widespread rainfall and strong winds over the Philippines during the last week of May 2023. (Source: Himawari-9 satellite surveillance)

Figure 4: Hotspot counts for the northern ASEAN region for May (2019-2023) based on NOAA-20 satellite surveillance. Hotspot counts were generally comparable to the counts in previous years, with majority of the hotspots detected in Lao PDR and Myanmar.

Figure 5: Hotspot counts for the southern ASEAN region for May (2019-2023) based on NOAA-20 satellite surveillance. Hotspot counts were slightly higher than the counts in previous years due to the gradual onset of the traditional dry season towards the end of May 2023.

Figure 6: Distribution of hotspots detected in May 2023 based on NOAA-20 satellite surveillance. Scattered hotspots were persistent over northern parts of Thailand and Lao PDR, as well as in parts of Myanmar and Viet Nam. Elsewhere in the ASEAN region, there were isolated and short-lived hotspots over the fire-prone areas in southern Sumatra and western Kalimantan.

Figure 7: Maximum fire intensity in May 2023 based on NOAA-20 satellite surveillance. The overall fire intensity was moderate over much of the Mekong sub-region, but particularly high over northern Lao PDR where clusters of hotspots persisted.

Figure 8: Number of days with moderate to dense smoke haze observed in May 2023 based on satellite imagery, ground observations, and air quality reports. Hazy conditions persisted mainly over western and northern parts of the Mekong sub-region.

Figure 9: Moderate smoke haze was observed in eastern Myanmar, northern Thailand and northern Lao PDR on 6 May 2023. Blown by the prevailing winds, transboundary smoke haze was observed to drift eastwards across northern Thailand, northern Lao PDR, and parts of Viet Nam. (Source: NOAA-20 satellite surveillance)

Review of Regional Haze Situation for April 2023

1.1 The Northeast Monsoon conditions gradually gave way to the inter-monsoon as the monsoon rainband shifted northwards towards the Equator in April 2023. The prevailing winds over the Mekong sub-region blew mostly from the southeast or southwest. For the rest of ASEAN region, the prevailing winds were light and variable in direction except over the Philippines where the prevailing winds blew from the northeast or east (Figure 1).

1.2 The prevailing dry conditions over the Mekong sub-region persisted for most of April 2023, although some showers returned over parts of the sub-region towards the end of the month. While wet weather was generally observed over the rest of the ASEAN region, it was dry over the Philippines. Parts of Peninsular Malaysia and Borneo also experienced brief period of drier conditions during the period (Figure 1).

1.3 Under the influence of the prolonged dry conditions, the hotspots counts in the Mekong sub-region during the review period were mostly higher compared to the previous years. In particular, the hotspot counts for Lao PDR and Myanmar in April 2023 were the highest in 5 years (Figure 2). In the southern ASEAN region, the hotspot counts were generally lower than or comparable to the previous years except for Kalimantan where hotspot counts were slightly higher than the previous years (Figure 3).

1.4 The elevated hotspot and smoke haze activity persisted over the Mekong sub-region for most of April 2023. Scattered to widespread hotspots were detected over may parts of the sub-region. In particular, clusters of hotspots were persistent and more intense (Figure 5) over parts of Myanmar as well as the northern parts of Thailand and the northern and central parts of Lao PDR. The return of the showers helped to alleviate the hotspot situation towards the end of the month. Elsewhere in the ASEAN region, isolated hotpots were detected in the Philippines, Peninsular Malaysia, Sumatra and Borneo but most of them were short-lived (Figure 4).

1.5 Widespread moderate to dense transboundary smoke haze was observed to blanket the eastern parts of Myanmar as well as the northern parts of Thailand, Lao PDR and Viet Nam on many days of the month. Moderate to dense smoke haze was also observed on many days over the northern, western and central parts of Myanmar (Figure 6 & 7). Moderate smoke haze was observed over the central parts of Thailand on some days of the month (Figure 6 & 8). In view of the improving hotspot and smoke haze situation with the return of shower activities towards the end of the month, the Alert Level for the Mekong sub-region was downgraded from Alert Level 3 to Alert Level 2 on 24 April 2023. For the southern ASEAN region, localized smoke plumes were observed to emit from isolated hotspots along the east coast of Peninsular Malaysia and Sumatra on some days during brief drier periods.

Review of Regional Haze Situation for March 2023

1.1 In March 2023, the ASEAN region continued to experience Northeast Monsoon conditions. Over areas north of the equator, the prevailing winds blew mainly from the northeast although light and variable winds prevailed over most parts of the Mekong sub-region. The prevailing winds over areas south of the Equator blew mostly from the west or northwest. As the Northeast monsoon conditions gradually weakened in the last week of the month, the prevailing winds over most of the ASEAN region started to turn light and variable on several days. (Figure 1).

1.2 The dry conditions over the Mekong sub-region and northern Philippines persisted throughout the review period of March 2023, except for isolated shower activities in some parts of the sub-region on a few days. Elsewhere in the ASEAN region, generally wet conditions were observed in many areas. (Figure 1).

1.3 For March 2023, the hotspot counts in the Mekong sub-region were higher or comparable to previous years under extended dry conditions, leading to an increase in overall hotspot activity (Figure 2). In particular, the highest hotspot activity was detected in Lao PDR, and the hotspot counts for Lao PDR were the highest in 5 years. For the southern ASEAN region, hotspot activity remained generally subdued and the hotspot counts were generally lower than in previous years (Figure 3).

1.4 Scattered to widespread hotspots were detected in the Mekong sub-region during the continued dry weather conditions. Clusters of hotspots were more intense and persistent in eastern and central Myanmar, Lao PDR, northern Thailand, and northeastern Cambodia. Isolated hotspots were also detected in northern Viet Nam. Over the southern ASEAN region, few hotspot activities were detected but most of them was short-lived (Figure 4).

1.5 The overall fire intensity in the Mekong sub-region had increased in March 2023, particularly over the fire-prone areas in Lao PDR, eastern and central Myanmar. (Figure 5). Widespread transboundary moderate to dense smoke haze was observed in the vicinity of the hotspot clusters in eastern Myanmar, northern and central Thailand, Lao PDR and northern Cambodia (Figure 6, 7 and 8) on many days. With the deteriorating hotspots and haze situation, Alert Level 3 was issued for the Mekong sub-region on 2 Mar 2023. Localised smoke plumes and occasional hazy conditions were also observed in northern Viet Nam on some days.

Review of Regional Haze Situation for February 2023

1.1 The ASEAN region continued to experience Northeast Monsoon conditions in February 2023. Over areas north of the equator, the prevailing winds blew mainly from the northeast even though the winds were mostly light and variable in direction over the Mekong sub-region. For areas south of the equator, the prevailing winds blew mostly from the west or northwest (Figure 1).

1.2 Dry conditions persisted over the Mekong sub-region throughout the review period of February 2023, except for isolated shower activities in the southern parts of the sub-region on some days. Elsewhere in the ASEAN region, rainy weather was observed in many areas. However, parts of Peninsular Malaysia and the northern Philippines experienced brief periods of drier weather. (Figure 1).

1.3 Prolonged dry conditions over the Mekong sub-region led to an increase in overall hotspot activity in February 2023 and the hotspot counts in the Mekong sub-region were higher or comparable to previous years (Figure 2). In particular, the highest hotspot activity was detected in Myanmar, and the hotspot counts for both Myanmar and Lao PDR were the highest in 5 years. For the southern ASEAN region, hotspot activity remained generally subdued and the hotspot counts were generally lower than in previous years (Figure 3).

1.4 Hotspot activity was widespread and persistent over the Mekong sub-region during the review period of February 2023. On many days, clusters of hotspots were detected in parts of Lao PDR, northern and eastern Cambodia, northern and central Myanmar, and northern Thailand. Isolated hotspots were also detected in northern Viet Nam. Over the southern ASEAN region, few hotspot activities were detected but most of them was short-lived (Figure 4).

1.5 The overall fire intensity in the Mekong sub-region had increased in February 2023, particularly over the fire-prone areas in Lao PDR, northern and central Myanmar, northern and eastern Cambodia, and northern Thailand (Figure 5). As a result, moderate to dense smoke haze was observed in the vicinity of the hotspot clusters in Myanmar, Thailand, and Cambodia (Figure 6, 7, 8 and 9) on many days. Localised smoke plumes and occasional hazy conditions were also observed in northern Viet Nam on some days.

Review of Regional Haze Situation for January 2023

1.1 Northeast Monsoon conditions continued to be observed over the ASEAN region in January 2023, with the prevailing low-level winds blowing predominantly from the northeast or east over areas north of the Equator and mainly from the west or northwest for areas south of the Equator (Figure 1). The strengthening of high-pressure systems over the northern Asian continent also brought a surge of strong northeasterly winds or monsoon surge over the South China Sea during the last week of January 2023.

1.2 In January 2023, dry weather prevailed over much of the Mekong sub-region under the influence of the Northeast Monsoon. As a result of the persistent dry conditions, an escalation in hotspot activity and development of smoke haze was observed in many parts of the sub-region from the second half of the month. On 27 January 2023, Alert Level 2 was activated for the Mekong sub-region as hotspot counts were persistently high and there was an increasing risk of transboundary haze. Elsewhere, rainy weather prevailed over the southern ASEAN region and the Philippines on most days of the month. In particular, monsoon surges contributed to increased rainfall over southern Peninsular Malaysia, Singapore, western Borneo, central Sumatra, and southern Philippines (Figure 1).

1.3 For January 2023, hotspot counts in the Mekong sub-region were slightly elevated compared to the same review period in 2022 (Figure 2). In particular, the highest hotspot activity was detected in Cambodia, and the hotspot count for Lao PDR and Viet Nam was slightly higher than the past 5 years. For the southern ASEAN region, hotspot activity remained generally subdued and the hotspot counts were lower or comparable to those in previous years (Figure 3).

1.4 During the review period, hotspot activity was widespread over the Mekong sub-region. On many days, clusters of hotspots were detected in northern and eastern Cambodia, as well as central Myanmar. Persistent hotspots were also detected in northern Viet Nam, as well as the northern and northeastern regions of Thailand. Over the southern ASEAN region, few hotspots were detected but most of them were short-lived (Figure 4).

1.5 The overall fire intensity in the Mekong sub-region had increased in January 2023, particularly over the fire-prone areas in central Myanmar, and northern and eastern Cambodia (Figure 5). As a result, persistent and moderate smoke haze was observed in the vicinity of the hotspot clusters in Myanmar and Cambodia (Figure 6, 7, and 8). Localised smoke plumes and occasional hazy conditions were also observed in northern Thailand, northern Viet Nam, and parts of Lao PDR.

Review of Regional Haze Situation for December 2022

1.1 In December 2022, the Northeast Monsoon was well established over the ASEAN region as the predominant low-level winds blew from the northeast over areas north of the Equator and blew from the west or northwest over areas south of the Equator. The northeasterly winds strengthened at times, bringing a monsoon surge over the South China Sea and parts of the Mekong sub-region (Figure 1).

1.2 During the month, dry conditions were experienced over most parts of the Mekong sub-region except for the southeastern parts of the sub-region where some rainfall was observed. Alert Level 1 for the onset of the dry season in the northern ASEAN region was issued on the 15 December 2022. Wet weather was experienced elsewhere in the ASEAN region with the highest rainfall observed over the eastern parts of the Peninsular Malaysia and the southern parts of Thailand and the Philippines (Figure 1), under the influence of the monsoon surge. Floods and landslides were also reported in these areas on several days during the month which resulted in several fatalities and displacement of people from their homes.

1.3 1.3 There was an increase in the overall hotspot activities in the Mekong sub-region following the onset of the dry conditions over the sub-region in December 2022 with the highest hotspot activity detected in Cambodia (Figure 2). In the southern ASEAN region, hotspot activities were mostly subdued due to the prevailing wet weather (Figure 3). While the hotspot activities in ASEAN region were mostly comparable to the same month in previous years, there was a noticeable increase in the hotspot activities in Cambodia compared to the last two years.

1.4 In the northern ASEAN region, isolated to scattered hotspots were detected mostly in the Mekong sub-region. The hotspots were more persistent in the northern and eastern parts of Cambodia, the southern parts of Myanmar, the northern parts of Viet Nam and the northern and central parts of Thailand (Figure 4). While the overall fire intensity of hotspots was low, localised smoke plumes were observed to emanate from hotspots in the eastern parts of Cambodia and northern parts of Viet Nam where the fire intensity was slightly higher (Figure 5). In the southern ASEAN region, hotspot activities were subdued due to the wet weather with few hotspots detected in Sumatra, Kalimantan and Sulawesi.

Review of Regional Haze Situation for November 2022

1.1 The inter-monsoon conditions gradually made way for the Northeast Monsoon over the ASEAN region in November 2022. The prevailing low-level winds over the northern ASEAN region blew from the northeast to east while the winds over most parts of the southern ASEAN region were light and variable in direction (Figure 1).

1.2 Most of the ASEAN region experienced wet weather conditions during November 2022, except for the northern, western and central parts of the Mekong sub-region where the conditions were relatively drier. Over the northern ASEAN region, rainfall amount was higher over the southern Mekong sub-region, coastal areas of Viet Nam and the Philippines. Widespread rainfall fell over much of the southern ASEAN region (Figure 1).

1.3 For November 2022, overall hotspot activities were mostly subdued due to the prevailing rainy conditions over the ASEAN region. Majority of the hotspots in the northern ASEAN region were detected in Myanmar, but the hotspot counts for the whole ASEAN region were generally lower or comparable to the counts in previous years (Figures 2 and 3).

1.4 Throughout the November review period, few to isolated hotspots were detected in the ASEAN region. While these hotspots were mostly short-lived, hotspots were relatively more persistent in the southern parts of Myanmar, central and northern Viet Nam, as well as central Thailand (Figure 4). On most days, no discernable smoke plumes were observed.

1.5 The fire intensity of hotspots detected over the ASEAN region was generally low in November 2022 (Figure 5). No significant smoke haze was observed from satellite imagery.