Rajshahi's 45.1C of 1972 is still Bangladesh's record: why the south-west runs hottest

April and May have long been Bangladesh's months of fierce heat, but the hot season is stretching into September and later. Against that background, BBC Bangla went through the Bangladesh Meteorological Department (BMD) records on 21 April 2026 to show when and where the country had been hottest. The BMD runs 48 stations and has kept temperature records since 1947. The highest reading in that archive is 45.1 degrees Celsius at Rajshahi on 18 May 1972.

The top readings in the BMD record cluster in a handful of places:

• Rajshahi, 18 May 1972: 45.1 degrees, the national record
• Rajshahi, April 1980: 44.4 degrees
• Bogura, April 1989, and Ishwardi, May 1970: 44 degrees
• Bogura, May 1958: 43.9 degrees
• Jashore (1963), Rajshahi (1985) and Jashore (2024), all in April: 43.8 degrees

Jashore's 43.8 degrees came on 30 April 2024, the same day Chuadanga reached 43.7 degrees, the district's highest since its weather observatory opened on 12 December 1988. Chuadanga had earlier recorded 43.5 degrees on 1 May 1995, 43 degrees on 25 April that year and 43.3 degrees on 4 May 1989.

BMD meteorologist Abul Kalam Mallik told BBC Bangla that gusty, stormy wind is what relieves extreme heat. "In the years when the highest temperatures were recorded, there were fewer kalbaishakhi storms, or Delhi, Uttar Pradesh and West Bengal may have been very hot and hot winds entered Bangladesh from there," he said. He noted that a station on the plains covers 18 to 20 kilometres and a hill station 8 to 10, so treeless, crowded places with factories and brick kilns may be hotter still without being measured.

Meteorologist A K M Nazmul Haque gave BBC Bangla three reasons. First, the wide plains of Chuadanga, Jashore, Meherpur and Khulna, and of West Bengal to their west, let heat travel directly by conduction. Second, water vapour from the Bay of Bengal enters the region from the south-west. Third, and most important: from 21 March to 21 June the sun's strongest rays fall around the 23-degree parallel, and Bangladesh lies between 22 and 26 degrees north. Meteorologists told Prothom Alo in April 2024 that over the previous 43 years Jashore had the most heatwave days, followed by Chuadanga and Dhaka.

Mr Mallik said wind speed and humidity shape how hot it feels. In 2024 a 35-day heatwave ran from 1 April to 5 May, breaking a 76-year record, yet dry, moving air kept Chuadanga and Rajshahi less uncomfortable, while Patuakhali, Barishal, Barguna and Cox's Bazar felt worse at lower temperatures because of moisture from the sea. When the gap between day and night temperatures falls below 10 degrees the heat is severe, at five degrees it is stifling, and below five there is a risk of hot winds and heatstroke.

Mymensingh and Sylhet stay more bearable thanks to haors and hills. Moist air from the Bay of Bengal is forced up by the hills, forms cloud and falls as rain, and warm and cool air mix in the folds of the hills.

The BMD classes 36 to 38 degrees as a mild heatwave, 38 to 40 as moderate, 40 to 42 as severe and above 42 as extreme. BBC Bangla noted that above 35 degrees the body's ability to cool itself is impaired, a direct hazard for farm workers in the fields. At a BRAC seminar in May 2024, experts said the prolonged heat of that April had threatened boro rice, made mango buds drop and caused a 25 per cent loss in milk, egg and meat production.

For 2026, meteorologists expected the year to be warmer than normal, with April close to normal. "The years 2022 to 2027 will be warm worldwide, and Bangladesh is no exception," Mr Mallik said, adding that with more kalbaishakhi storms the heat would not surpass 2024. Forecasters indicated six to eight heatwaves between April and June, three or four of them severe.

Photo: Nahid Sultan / Wikimedia Commons (CC BY-SA 4.0)

Sources: BBC Bangla, Prothom Alo (30 April 2024, 27 April 2024, 25 May 2024 and 7 May 2025), Wikipedia (Rajshahi)