Thailand’s Meteorological Department has forecast that many areas in the North, Northeast, East and Central Plain will either be hot or extremely hot between tomorrow and Thursday.

On Tuesday, the sun will shine directly over Bangkok.

“It will happen around 12.16pm Tuesday,” National Astronomical Research Institute of Thailand deputy director Saran Poshyachinda said.

He declined to predict if Tuesday would be the hottest day of the year, explaining that other factors would determine that, such as cloud cover and humidity.

The hottest day recorded in Thailand this year was the 44 degrees Celsius in Sukhothai province mid-April. In Singapore, the hottest day on record was April 19, as authorities urged people to take measures to avoid a heat stroke and other related illnesses.

The mercury shot to 36 degrees Celsius at Choa Chu Kang, but the average daily temperature hit a record 30.6 degrees, up from the previous high of 30.2 degrees on June 22 last year.

The average daily temperatures were measured at the Changi climate station, which is used as Singapore’s reference station.

April is typically the warmest month of the year, with a long-term mean monthly temperature of 28 degrees.

This year, Singapore has really been feeling the heat.

During a three-day period the highest temperatures recorded ranged from 35.1-36.4 degrees. A week earlier, it had soared to a 10-year high of 36.7 degrees.

But the sizzling temperatures have stopped short of a heatwave, after thunderous showers offered some respite on Wednesday.

A heatwave occurs when the daily maximum temperature is at least 35 degrees on three consecutive days, and the daily mean temperature throughout the period is at least 29 degrees. In a joint advisory with the ministries of Social and Family Development, Education, Manpower and Health on Wednesday, Singapore’s National Environment Agency said high temperatures were common during the inter-monsoon months of April and May when there was strong solar heating but light winds.

“In addition, the prevailing strong-to-moderate El Nino [weather effect] is a contributing factor to the current warm conditions,” it added.

But it noted that temperatures in Singapore were unlikely to reach 40 degrees, as experienced recently in northern Peninsular Malaysia, due to the moderating effect of surrounding seas on the temperature.

The agencies said people could minimise the risk of heat-induced illnesses by wearing loose-fitting, heat-permeable and light-coloured clothing and taking more breaks between activities, among other things.

Sustained outdoor activities at schools, child-care centres, kindergartens and homes should also be minimised during the hotter period of the day and the intensity of these activities should be moderated. Employers should schedule heavy physical or outdoor work for the cooler parts of the day.

The Defence Ministry said the Singapore Armed Forces had in place a work-rest cycle guideline, which ensured that servicemen train and operate safely even when outdoor temperatures were high.