The Meteorological Department warned all regions Sunday to brace for thunderstorms this week with the northeastern region likely to be hit first.
In its third such advisory, the department said residents nationwide, including Bangkok and the surrounding provinces, should be prepared for thunderstorms caused by a high-pressure system from China.
From Monday until Friday, the high pressure zone from China will cover the upper part of the country where it will collide with hot air and result in outbreaks of thunderstorms, the department said.
Thunderstorms, lightning, strong winds and hail are forecast.
The northeastern region will be hit first, followed by the northern region, the central provinces, the eastern region and the southern region. Bangkok and its vicinity will be affected from Wednesday to Friday.
According to the department, people should steer clear of outdoor areas during storms and keep away from unstable structures.
Strong winds could knock down trees and billboards while hail could cause injuries.
The department also warned about lighting strikes and advised farmers to take precautions to protect their crops because thunderstorms can cause significant damage.
People are also urged to closely follow weather reports and warnings.
In addition, the weather office has advised the public to take precautions to keep themselves safe during the extreme heat likely early this week.
Temperatures between 35-39 degrees Celsius, with isolated thunderstorms, are predicted for Bangkok.