Seasonal Forecast for October – December 2022

Updated 30 September 2022

Southwest Monsoon conditions are typically expected to transition gradually to the inter-monsoon period in late October and early November 2022. As the monsoon rainband moves southwards towards the Equator, the prevailing low-level winds over most parts of the ASEAN region are likely to be light and variable in direction. With the onset of the inter-monsoon, shower activities are expected to increase over most parts of the equatorial region.

For the October to December (OND) 2022 period, an increased chance of above-normal rainfall is predicted for much of the ASEAN region, apart from an increase in chance of below-normal rainfall over parts of the western Maritime Continent. La Niña conditions are predicted to continue at least until December 2022. The negative Indian Ocean Dipole (IOD) is expected to weaken towards the end of the year. Both La Niña and negative IOD events tend to bring wetter conditions to parts of the ASEAN region. Warmer-than-normal temperature is predicted for many parts of the ASEAN region, with the exceptions of below- to near-normal temperatures over much of the Mainland Southeast Asia as well as parts of the equatorial region.

The overall hotspot and smoke haze situation is likely to stay subdued in October and November 2022, with above-normal rainfall forecast for much of the ASEAN region. Isolated hotspots and localised smoke plumes may occur in fire-prone areas during brief periods of drier weather. Hotspot activities in the northern ASEAN region are likely to increase towards December 2022 as the traditional dry season sets-in, increasing the risk of smoke haze development for the Mekong sub-region.

The qualitative outlook is assessed for the region in general and based on the latest runs from models provided by the SEA RCC-Network LRF node. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.

For October 2022, models predict above-normal rainfall over much of the southern ASEAN region.

 

For October 2022, above-normal rainfall is predicted over much of the southern ASEAN region, with highest likelihood over southern Maritime Continent (Figure 4). The exception is over parts of the western Maritime Continent where overall an increased chance of below-normal rainfall is predicted. The models’ skill is moderate to good for above-normal rainfall over most of the southern ASEAN region, apart from over the western Maritime Continent where the models’ skill is low.

For the northern ASEAN region, above-normal rainfall is predicted (Figure 4) but with relatively lower likelihood than the southern ASEAN region. While the UK Met Office model predicts an increased chance of above-normal rainfall for much of the region (Figure 3), the ECMWF and NCEP models show near- to above-normal rainfall for much of the region (Figures 1 and 2, respectively). The models’ skill is low for most of the northern ASEAN region, although it is low to moderate for the eastern half of the northern ASEAN region.

Figure 1a: Rainfall tercile summary predictions of NCEP model for October 2022. Figure 1b: Rainfall tercile summary predictions of ECMWF model for October 2022 (contains modified Copernicus C3S information).

Figure 1c: Rainfall tercile summary predictions of UK Met Office model for October 2022 (contains modified Copernicus C3S information). Figure 1d: Rainfall tercile summary predictions of multi-model ensemble model for October 2022 (contains modified Copernicus C3S information).

The qualitative outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted. More outlook and verification plots, including for tercile and quintile probabilistic forecasts for rainfall, are in the “Model products and verification: NCEP, ECMWF, UK Met Office” on the SEA-RCC Network LRF Node webpages.


For OND 2022, above-normal rainfall is predicted for much of the ASEAN region.

 

For OND 2022, based on the multi-model ensemble (Figure 4), there is an increased chance of above-normal rainfall for much of the ASEAN region. The highest likelihood for all three models is over the southern Maritime Continent, while there is only a relatively small increase in chance over much of Mainland Southeast Asia. Model skill is moderate to good over the southern Maritime Continent, while low to moderate over Mainland Southeast Asia and the Philippines.

The exception to the wetter conditions is over the western Maritime Continent and northern Borneo where below-normal rainfall is predicted. However, model skill is low at this time of year for the western Maritime Continent.

Figure 2a: Rainfall tercile summary predictions of NCEP model for OND 2022. Figure 2b: Rainfall tercile summary predictions of ECMWF model for OND 2022 (contains modified Copernicus C3S information).

Figure 2c: Rainfall tercile summary predictions of UK Met Office model for OND 2022 (contains modified Copernicus C3S information). Figure 2d: Rainfall tercile summary predictions of multi-model ensemble model for OND 2022 (contains modified Copernicus C3S information).

The qualitative outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted. More outlook and verification plots, including for tercile and quintile probabilistic forecasts for rainfall, are in the “Model products and verification: NCEP, ECMWF, UK Met Office” on the SEA-RCC Network LRF Node webpages.


For October 2022, the models predict above-normal temperature over much of the ASEAN region.

 

For October 2022, below- to near-normal temperatures are favoured over parts of the equatorial region and southern Mainland Southeast Asia, with above-normal temperature favoured elsewhere. For October 2022, an increased chance of above-normal temperature is predicted over much of the ASEAN region based on the multi-model ensemble (Figure 4), apart from over parts of the equatorial region and southern Mainland Southeast Asia where below- to near-normal temperature is predicted. The UK Met Office model (Figure 3) predicts the highest spatial coverage of above-normal temperature, followed by the NCEP model (Figure 1) and then the ECMWF model (Figure 2).

All three models predict near-normal temperature over southern Mainland Southeast Asia. While the NCEP and UK Met Office models predict near-normal temperature over parts of the central ASEAN equatorial region and Papua, the ECMWF model predicts below- to near-normal temperature over much of the equatorial region.

The model skill is low to moderate for near-normal and below-normal temperature, and relatively good for above normal temperature for most of the ASEAN region.

Figure 3a: Temperature tercile summary predictions of NCEP model for October 2022. Figure 3b: Temperature tercile summary predictions of ECMWF model for October 2022 (contains modified Copernicus C3S information).

Figure 3c: Temperature tercile summary predictions of UK Met Office model for October 2022 (contains modified Copernicus C3S information). Figure 3d: Temperature tercile summary predictions of multi-model ensemble model for October 2022 (contains modified Copernicus C3S information).

The qualitative outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted. More outlook and verification plots, including for tercile and quintile probabilistic forecasts for temperature, are in the “Model products and verification: NCEP, ECMWF, UK Met Office” on the SEA-RCC Network LRF Node webpages.


For OND 2022, below- to near-normal temperatures are favoured for parts of the equatorial region and much of the Mainland Southeast Asia, with above-normal temperature favoured elsewhere.

 

For OND 2022, based on the multi-model ensemble (Figure 4), below- to near-normal temperatures are predicted over parts of the equatorial region and much of Mainland Southeast Asia, while above-normal temperatures are predicted for northwest Mainland Southeast Asia and parts of the western and eastern Maritime Continent. All models (Figures 1-3) predict below-normal temperatures over central and eastern Mainland Southeast Asia, but with a relatively lower likelihood. The ECMWF model shows the largest extent of below-normal temperature over parts of the southern Maritime Continent, followed by the NCEP model.

The model skill for below- and above-normal temperatures for most of the ASEAN region is moderate to good. The model skill for near-normal temperature is low to moderate over the equatorial region and Mainland Southeast Asia.

Figure 4a: Temperature tercile summary predictions of NCEP model for OND 2022. Figure 4b: Temperature tercile summary predictions of ECMWF model for OND 2022 (contains modified Copernicus C3S information).

Figure 4c: Temperature tercile summary predictions of UK Met Office model for OND 2022 (contains modified Copernicus C3S information). Figure 4d: Temperature tercile summary predictions of multi-model ensemble model for OND 2022 (contains modified Copernicus C3S information).

The qualitative outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted. More outlook and verification plots, including for tercile and quintile probabilistic forecasts for temperature, are in the “Model products and verification: NCEP, ECMWF, UK Met Office” on the SEA-RCC Network LRF Node webpages.