Temperatures are expected to exceed 40C in all regions of Thailand this month and in April, the Meteorological Department has warned.
Kornravee Sitthichitvapak, director-general of the weather agency, said temperatures will be 1-2C higher than the seasonal average this summer.
Areas experiencing very hot weather are anticipated to reach temperatures above 40C, with the North and the Northeast expected to experience hot and very hot weather.
However, these extremes will not occur every day but only in specific areas and periods, she added.
Temperatures are projected to reach 40C in many areas, including the Central Plains and Bangkok, from March to April.
Ms Kornravee said the highest recorded temperature in Thailand was 44.6C in Tak in 2016. In Bangkok, the highest temperature last year was 41C.
While Thailand has not seen the mercury climb above 50C, the forecaster previously emphasised the heat index figures reflect how temperatures "feel" rather than precise measurements, he said.
According to the department, the highest temperature recorded was 42C in tambon Bua Chum of Chaibadan district in Lop Buri on Wednesday, followed by 41.2C in Roi Et and 41C in Kanchanaburi.
Provinces in the Northeast, such as Chaiyaphum, Nakhon Ratchasima's Chok Chai district, Buri Ram, Mukdahan, Roi Et, Loei and Sakon Nakhon, reported temperatures slightly higher than 40C.
The Meteorological Department also warned that summer storms and gusty winds are expected in the northern and northeastern regions as well as the Central Plains, including Bangkok, from today until Sunday.
A high-pressure system from China is expected to cover the Northeast of Thailand and the South China Sea today.
Southerly and southeasterly winds will bring moisture from the South China Sea and the Gulf to the upper part of the country, resulting in hot to very hot weather, according to the department's latest update.
Given these conditions, summer storms, gusty winds, hail, and lightning strikes are predicted for some areas in the lower North, the Northeast, the Central Plains, including Bangkok and its vicinity, and the East from today until Monday.
People living in the upper part of the country should take precautions against severe weather conditions by avoiding risky outdoor areas.
The weather agency advises people to stay away from large trees, unsecured structures and billboards. Farmers should take precautions against crop damage.
Meanwhile, 57 out of the country's 77 provinces were blanketed with hazardous levels of ultrafine dust yesterday morning, with 27 provinces, mostly in the North and the Northeast, experiencing red (seriously harmful) levels of pollution.
The Geo-Informatics and Space Technology Development Agency (Gistda) reported at 11am yesterday that the highest level of PM2.5 was detected in the northernmost province of Chiang Rai, at 128.8 microgrammes per cubic metre (µg/m³) of air over the past 24 hours.
The government's safe threshold is 37.5 µg/m³, while the World Health Organization (WHO) guidelines recommend nothing above 25 µg/m³.
After the worst level was recorded in Chiang Rai, Tak had a PM2.5 level of 120.1 µg/m³, followed by Chiang Mai (116.5 µg/m³), Mae Hong Son (113.8 µg/m³) and Lamphun (113.8 µg/m³).
