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.
Meanwhile, people gathered to enjoy a late frost at the top of Thailand's highest mountain, in Chiang Mai, on Thursday morning.
The announcement said the cool season had already ended and summer officially began on Wednesday.
The immediate outlook 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.
Somkhuan Tonjan, director of the forecast sub-division, said 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.
The El Nino weather pattern remains strong, though there is a weakening trend. This would result in dry weather, he said. Rainfall could be 30% below normal and its distribution would not be favourable.
This would result in drought outside irrigation zones. There may be shortages of water for domestic use and for the agricultural sector, Mr Somkhuan said.
In stark 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. In lowland areas of Chiang Mai province, temperatures were 14-16°C.
The cool weather and frost, or moei khab, drew many tourists to the Kiew Mae Pan viewpoint on Doi Inthanon.
Frost coats leaves at the top of Doi Inthanon in Chiang Mai province on Thursday morning, as the Meteorogical Department announced the start of a hot, dry summer. (photo: Panumet Tanraksa)
Tourists enjoy the cool weather at Doi Inthanon. (Photo: Panumet Tangraksa)