Seasonal Forecast for November 2025 – January 2026
Updated 3 November 2025
The Southwest Monsoon gradually transitioned into the inter-monsoon period during October 2025. During this period, prevailing winds are typically light and variable in direction across most of the region. With the monsoon rain band located close to the Equator, increased shower activity can be expected over the equatorial ASEAN region. Northeast Monsoon conditions have subsequently set in for some parts of the northern ASEAN region in October 2025 and will gradually onset for the rest of the region during November – December. These conditions are characterised by prevailing winds blowing predominantly from the northeast.
For the November 2025 to January 2026 (NDJ) period, above-normal rainfall is predicted for much of the southern and eastern Maritime Continent and southern Mainland Southeast Asia. Current ENSO state is La Niña Watch, with La Niña conditions predicted to become established in October 2025 and persist until at least the end of 2025. A negative Indian Ocean Dipole (IOD) is present and is predicted to persist until December 2025. Both La Niña and negative IOD events tend to bring wetter conditions to parts of Southeast Asia. Above-normal temperature is predicted for most of the Maritime Continent and northwestern Mainland Southeast Asia for NDJ 2025-2026.
Over the southern ASEAN region, the dry season ended on 22 October 2025. While below-normal rainfall is forecast over parts of the region during the outlook period, the hotspot activity is expected to remain subdued under the overall wet weather conditions. However, isolated hotspots with localised smoke plumes may still occur over areas experiencing periods of drier conditions. While above-normal rainfall is expected over most parts of the northern ASEAN region, the hotspot and smoke haze activity is expected to progressively intensify over the fire-prone areas of the Mekong sub-region, as its traditional dry season gradually set in with the onset of the Northeast Monsoon.
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 November 2025, above-normal rainfall is predicted over the southern and eastern Maritime Continent and much of Mainland Southeast Asia.
For November 2025, above-normal rainfall is predicted over most of the southern and eastern Maritime Continent based on the multi-model ensemble (Figure 1), with below-normal rainfall over parts of the northwestern and central regions. Most models (more than six models, Figure 2) predict above-normal rainfall as the dominant tercile for the southern and eastern regions. In general, at least four out of the nine models predict below-normal rainfall over the northwestern Maritime Continent and northern Borneo.
For Mainland Southeast Asia, above-normal rainfall is predicted over much of the region. Most of the region has at least some models (4 – 6) predicting above-normal rainfall, with the southeastern and northwestern regions having most models (more than six models) predicting above-normal rainfall.
Model skill is good for predicting above-normal rainfall over the southern and northeastern Maritime Continent and southeastern Mainland Southeast Asia. Model skill is low to moderate elsewhere in Southeast Asia.
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| Figure 1: Rainfall tercile summary predictions of the multi model ensemble for November 2025 (contains modified Copernicus C3S information). | Figure 2: Number of models in agreement in the multi-model ensemble for the dominant tercile for November 2025. Where there no dominant tercile, it refers to the number of models with near-normal tercile (contains modified Copernicus C3S information). |
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| Figure 5: Average climatological rainfall’s lower tercile boundary for November based on CHIRPS (reference period: 1991-2020). | Figure 6: Average climatological rainfall’s upper tercile boundary for November based on CHIRPS (reference period: 1991-2020). |
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 NDJ 2025-2026, models predict above-normal rainfall over much of the southern and eastern Maritime Continent and southern Mainland Southeast Asia.
For NDJ 2025-2026, above-normal rainfall is predicted for much of the southern and eastern Maritime Continent, based on the multi-model ensemble (Figure 1). The highest probability of above-normal rainfall is over the southern Maritime Continent. Elsewhere in the Maritime Continent, below-normal rainfall is predicted over parts of the northwestern and central Maritime Continent. Most models agree on above-normal rainfall as the most likely tercile for the southern and eastern parts of the region (more than six models, Figure 2). For below-normal rainfall, a mix of some models (4 – 6) and most models (more than six models) agree with each other.
For Mainland Southeast Asia, above-normal rainfall is predicted over the southern and western regions. Most models agree on above-normal rainfall over the southeastern portion (more than 6 models), with some models (4 – 6 models) agreeing for the rest of the mentioned area. Mix of below-normal rainfall and no dominant tercile is predicted for most of northern Mainland Southeast Asia.
Model skill for predicting above-normal rainfall is good for the southern and eastern Maritime Continent and southeastern Mainland Southeast Asia. Model skill is poor to moderate elsewhere in the region.
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| Figure 1: Rainfall tercile summary predictions of the multi model ensemble for NDJ 2025 -2026 (contains modified Copernicus C3S information). | Figure 2: Number of models in agreement in the multi-model ensemble for the dominant tercile for NDJ 2025 – 2026. Where there no dominant tercile, it refers to the number of models with near-normal tercile (contains modified Copernicus C3S information). |
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| Figure 5: Average climatological rainfall’s lower tercile boundary for NDJ based on CHIRPS (reference period: 1991-2020). | Figure 6: Average climatological rainfall’s upper tercile boundary for NDJ based on CHIRPS (reference period: 1991-2020). |
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 November 2025, above-normal temperature is predicted over most of the Maritime Continent, with near-normal temperature predicted over much of central and eastern Mainland Southeast Asia.
For November 2025, above-normal temperature is predicted over most of the Maritime Continent and northwestern Mainland Southeast Asia (Figure 1). The likelihood of above-normal temperature is high over much of the equatorial region and eastern Maritime Continent. Most of the models (more than six models, Figure 2) predict above-normal temperature as the most likely tercile for the mentioned regions. Elsewhere over central and eastern Mainland Southeast Asia, near-normal temperature is predicted (Figure 1) with generally some models in agreement with each other (4 – 6, Figure 2). Model skill for predicting above-normal temperature is relatively good for most of the Maritime Continent and moderate for northwestern Mainland Southeast Asia. Model skill for predicting near-normal temperature is low to moderate for Mainland Southeast Asia.
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| Figure 1: Temperature tercile summary predictions of the multi model ensemble for November 2025 (contains modified Copernicus C3S information). | Figure 2: Number of models in agreement in the multi-model ensemble for the dominant tercile for November 2025. Where there no dominant tercile, it refers to the number of models with near-normal tercile (contains modified Copernicus C3S information). |
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| Figure 5: Average climatological temperature for November based on ERA5 (reference period: 1991-2020). |
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 NDJ 2025-2026, above-normal temperature is predicted over most of the Maritime Continent, with near-normal temperature predicted for central and eastern Mainland Southeast Asia.
For NDJ 2025-2026, above-normal temperature is predicted over most of the Maritime Continent while a mix of near- to above-normal temperature is predicted over Mainland Southeast Asia (Figure 1). Over most of the Maritime Continent and northwestern Mainland Southeast Asia, most models (more than six models) predict above-normal temperature as the most likely tercile. Over parts of central and eastern Mainland Southeast Asia, near-normal temperature is generally predicted. There is less agreement between models for these regions, with some models (4 – 6) predicting near-normal temperature. Model skill for predicting above-normal temperature is good for most of Southeast Asia, and generally moderate for predicting near-normal temperature for the mention region.
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| Figure 1: Temperature tercile summary predictions of the multi model ensemble for NDJ 2025-2026 (contains modified Copernicus C3S information). | Figure 2: Number of models in agreement in the multi-model ensemble for the dominant tercile for NDJ 2025-2026. Where there no dominant tercile, it refers to the number of models with near-normal tercile (contains modified Copernicus C3S information). |
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| Figure 5: Average climatological temperature for NDJ based on ERA5 (reference period: 1991-2020). |
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.
Frequently Asked Questions
What is a seasonal forecast?
A seasonal forecast provides forecast information about the general weather conditions at seasonal timescales up to several months ahead. Long range predictions rely on predicting components of the atmosphere and the oceans which show variations at large spatial and temporal scales. Among these key components is the sea-surface temperature – an important indicator in the El Niño Southern Oscillation (ENSO) cycle.
Example of probabilistic long range forecast using the multi-model ensemble. For areas nearby Peninsular Malaysia, the forecast is showing a probability of 50-70% of rainfall being in the below-normal (33%) tercile range. (Source: WMO LC LRF)
To account for the chaotic nature of the atmosphere, seasonal forecast adopts a probabilistic approach and the forecast weather condition is presented as an average over an extended period of time, usually with reference to climatology.
ASMC carries out monthly seasonal forecast predictions based on various seasonal model forecasts from the leading meteorological centres, supplemented by individual assessments from respective countries in South East Asia. The skillfulness of seasonal forecast relies greatly on the performance of seasonal models, which differ from one place to another and for different seasons of the year.
Receiver operating characteristic (ROC) score of UK GloSea5 seasonal hindcast for above-normal precipitation scenario for Dec – Feb (left) and May – Jul (right) over Asia region. Higher ROC score (indicated in red) means better model skill. (Source: UK Met Office)
For example, one way to assess the seasonal model skills is to examine the ROC score. From the figures above, we can see that ROC score map differs greatly from one season to another. During the period from Dec to Feb, a high ROC score region is observed mainly over the Philippines whereas during the period from May to Jul, a high ROC score region is observed over the near equatorial region such as Peninsular Malaysia and Sumatra.