Heatwaves in April getting longer

Mild to moderate heatwaves in the month of April have gotten longer over the years, according to preliminary data of a research.

Between 1981 and 2023, the shortest duration of an April heatwave was two days and the longest was 23 days, says Meteorologist Muhammad Abul Kalam Mallik, who has studied temperatures of April over 43 years.

Rajshahi, Jashore, Pabna, Chuadanga and Satkhira saw the highest number of hot days in April.

Temperatures between 36 and 40 degrees Celsius are considered mild to moderate heatwaves.

However, the number of days seeing severe, 40-42 C, and very severe, over 42 C, have not risen.

Severe to very severe heatwaves stayed for six days at most, says Mallik, a meteorologist at Bangladesh Meteorological Department. 

There were at least two days of mild to moderate heatwave in every April in the 43 years. In recent years, such hot days have sometimes persisted for more than three weeks.

The country is baking in extreme heat and this April has already seen four days of severe to very severe heatwaves.

According to the research which has not been published yet, districts in the northern, southern and southwestern part of the country were affected the most. Heatwaves prevailed for more than one third of April over some districts.

In the 43 years studied, there were 1,290 days in April. Dhaka saw 186 days of mild to extreme heatwave, Tangail 193, Satkhira 284, Rangamati 135, Bogura and Madaripur 146 each, and Faridpur 265.

Currently, a mild to very severe heatwave is sweeping over the country with the Met office saying that it will continue until the end of this month.

From 1981 to 1988, the number of hot April days was two; in 1988, it was five; in 1991, it was 10; in 1992, it was nine; in 1994, it was 16; in 1995, it was 23; in 2001, it was 17; in 2008, it was 16; in 2009, it was 17; in 2014, it was 23; and in 2023, it was 17.

When it comes to severe to very severe heatwaves, in 1989, there were three days; in 1992, five days; in 1995, four days; from 1997-2004, two days each year; in 2009-2010, four days each year; in 2014, six days; in 2016, two days; and in 2022-2023, three days each.

MET ISSUES ALERT FOR 72 HOURS

The Met office yesterday issued a heatwave alert for 72 hours.

Meteorologist AKM Nazmul Hoque said due to high levels of humidity, the weather feels four to five degrees hotter than it actually is.

The highest temperature this month, 42.6 C, was recorded in Chuadanga on April 21.

Nazmul said that the Met Office yesterday reissued a heatwave alert for 72 hours "so that different government agencies take necessary measures".

"We will issue the alert again as the temperatures may increase from Tuesday," he said.

There is no rainfall forecast for the country except one or two places in Sylhet, Mymensingh and Chattogram divisions.