This year's cold season is expected to begin in the fourth week of October and last until late February with temperatures in the Bangkok area likely to drop as low as 15°C, and chillier elsewhere, the Meteorological Department said.
The department said the arrival of the cold weather would be about a week later than usual.
The average minimum temperatures in Upper Thailand would be 20-21°C. The weather would be generally colder than last year, when the average minimum temperature was 21.0°C.
The lowest temperatures, 8-9°C, were expected in the North and Northeast regions. In Bangkok, the lowest temperatures would be 17-18°C and 15-16°C in its vicinity.
The coldest time would be December and January and mountain tops would range from cold (8.0-15.9°C) to very cold (below 8.0°C) with some frosts.
In the South, the weather would be cool (16.0-22.9°C) some days, mostly in the upper part of the region. There would be widespread rain, especially on the east coast, in November and December, with occasional heavy rain to heavy rain in some areas.
Wind waves would be 2-3 metres high in the Gulf of Thailand and 1-2m high in the Andaman Sea.
Also in November and December, there may be tropical storms over the Gulf of Thailand and South Thailand, bringing widespread rain and wind-waves of 3-4m high, the weather office said.