The Meteorological Department has announced the start of summer, with temperatures expected to peak at a blistering 45°C over the next few months in some areas.
The announcement said the cool season had already ended and summer officially began on Wednesday.
The forecast is for daily peaks averaging 35°C in the afternoon, helped by strong solar radiation and a southerly wind blowing over upper regions of the country.
The North and the Northeast could face cooler mornings until mid-March.
This year’s hot season is expected to end in mid-May, the department said.
Temperatures are forecast at 36-37°C on average this summer. Last year's summer average was 35.8°C.
March and April would be the hottest months, with 43-44°C highs. However, some areas could experience up to 45°C, above the record 44.6°C registered in Mae Hong Son province in 2016 and in Tak province last year.
In contrast, the temperature dropped to 3°C at the top of Thailand’s highest mountain, Doi Inthanon, in Chiang Mai, on Thursday morning, with frost coating the leaves of plants.