BANGKOK — 15 October 2026, Thailand’s winter season is expected to begin about a week later than average this year, with temperatures forecast to be warmer than normal and heavy rain posing flood risks in the South, the Thai Meteorological Department said.
Winter in upper Thailand is expected to begin in the third week of October and last until around mid-February 2027.
The average minimum temperature across upper Thailand is forecast at 22-23 degrees Celsius, about 2C above the normal average of 19.9C. The season is also expected to be less cold than last year, when the average minimum temperature was 19.6C.
The lowest temperatures are forecast at 10-12C in the upper parts of the North and Northeast. Bangkok is expected to see minimum temperatures of 19-21C, while surrounding provinces could experience lows of 18-20C.
The coldest period is expected from late December 2026 to early February 2027. Mountain peaks in the North and Northeast, along with other high-altitude areas, could experience very cold conditions and frequent frost.
South faces heavy rain and rough seas
The South will continue to experience widespread rain, particularly along the Gulf of Thailand coast in November and December. Heavy to very heavy rainfall could trigger flash floods, forest runoff and river overflows in several areas.
Waves in the Gulf of Thailand are forecast to reach 2-4 metres at times, while waves in the Andaman Sea are expected to reach 1-2 metres.
The department warned that low-pressure areas could develop in November and December, with a high chance of intensifying into tropical cyclones and moving close to or across the Gulf of Thailand and the South. Such systems could bring prolonged heavy rain, stronger winds and storm surges, with waves potentially reaching 3-4 metres.
The northeastern monsoon is expected to bring particularly wet conditions to the eastern South, from Chumphon province southward, from mid-October through early January. Thunderstorms could affect 60-80% of the area, with heavy rain in many places and very heavy rain in some locations.
Rainfall on the Andaman coast is expected to affect 30-50% of the area from mid-October to mid-November, with heavy rain in some places.
El Niño may bring warmer conditions
The department also expects El Niño to strengthen toward the end of 2026 and potentially persist into early 2027. The phenomenon could contribute to above-normal temperatures and a milder winter compared with last year.
Across the North and Northeast, cooler weather is expected to become more widespread from mid-November to early February, particularly in the upper parts of both regions. The central and eastern regions will generally experience cooler conditions during this period, especially in their northern areas.
Conditions are expected to become more variable later in the season, with warmer daytime temperatures and areas of dense morning fog. The North and Northeast are still likely to experience cool mornings.
Bangkok and surrounding provinces are forecast to have thunderstorms over 20-30% of the area from mid-October to mid-November, with cooler weather on some days, morning fog and possible gusty winds. From mid-November to early February, cooler conditions are expected to become more widespread before temperatures rise again later in the season.
