Department director-general Wanchai Sakudomchai on Tuesday advised against going outdoors in the afternoon on those days because the extreme heat could cause harm.

The sun will be at its zenith in Bangkok on Thursday (April 27), Wanchai said, but summer storms in some areas are likely to keep the temperature lower that day in and around the capital compared to other provinces.

The sun is at zenith at different times in different provinces this month and next, said Saran Poshyachinda, deputy director of the Science and Technology Ministry’s National Astronomical Research Institute of Thailand.

It was directly overhead, at its highest position relative to Earth’s orbit, in Yala’s Betong district on April 5, Phuket on April 10 and Pattaya on April 24.

In Bangkok the sun will be at zenith, casting minimal shadows, at 12.16pm on Thursday.

In Chiang Rai’s Mae Sai district the solar zenith occurs on May 19 at 12.17pm.

Saran pointed out that the sun at zenith does not necessarily mean the temperature will be at its highest. The heat level depends on other factors as well, such as rain, clouds, the monsoon’s influence and heat accumulated in the atmosphere.

Countries in the subtropics like Thailand see the sun at or near zenith two days a year at most, Saran said. It will reach zenith again over Bangkok on August 16 at 12.24pm.