Thailand still waiting for official start of winter as rain continues

Thailand has yet to officially enter the winter season in 2026, despite cooler conditions in some areas, as rainfall continues and the weather has not fully met the criteria used by the Thai Meteorological Department (TMD).

The department’s records show considerable variation in the start of winter over the past four years.

Thailand officially entered winter on October 23 in 2025, November 3 in 2024, November 14 in 2023 and October 29 in 2022.

Although temperatures have begun to fall in several areas this year, the presence of continued rainfall means cooler weather alone is not enough for the TMD to formally declare the start of winter.

Three conditions used to determine start of winter

The department considers three main meteorological conditions before announcing the seasonal change.

Minimum temperatures across upper Thailand must fall below 23 degrees Celsius on a sustained and widespread basis, bringing conditions into the cool-weather range.

Wind patterns must also change, with northeasterly or easterly winds prevailing at lower atmospheric levels, while upper-level winds shift to a westerly direction.

The third condition is a sustained decline in the amount and distribution of rainfall across upper Thailand.

The TMD’s current outlook shows that rain is still affecting several parts of the country. Its October 22 advisory forecasts continued rain, including heavy to very heavy rainfall in parts of the East and South through October 25, while thunderstorms are also expected in parts of upper Thailand.

Winter dates vary from year to year

Thailand normally begins transitioning from the rainy season into winter around the middle of October, with the winter period generally extending into mid-February.

However, the TMD notes that the transition period can remain unsettled for one to two weeks, with cooler conditions developing while thunderstorms may still occur, particularly in the lower Central region and the East.

The timing therefore differs from year to year according to actual temperature, wind and rainfall conditions rather than a fixed calendar date.

The public is advised to follow TMD announcements for confirmation of the official start of Thailand’s 2026 winter season and updates on changing weather conditions.