Winter lost to heat? Bangladesh records warmest season since 1948

Infographic: TBS

Summary:

• Bangladesh had its warmest winter since 1948, with no severe cold spells
• January 2024 was the hottest on record, breaking historical temperature trends
• February's average temperature was 1.4°C higher than usual across Bangladesh
• Increased water vapor and easterly winds contributed to warmer winter temperatures
• Heatwaves and reduced rainfall are expected in March, reaching 40°C

Bangladesh has experienced its warmest winter (December- February) since 1948, with January being the hottest on record and no severe cold, which is typically the coldest month of the season, experiencing two to three cold spells on average, according to the Met office data. 

"This winter was unusually warm, with minimal cold sensations. According to BMD temperature records from 1948 to 2024, it was the warmest winter season. January usually experiences two to three severe cold spells, but this year, not a single one occurred," Bangladesh Meteorological Department (BMD) official Muhammad Abul Kalam Mallik told TBS.

2024 was the warmest year on record globally, and 2025 is expected to follow a similar trend with early temperature rises, according to global forecasts.

The BMD predicts one to two heat waves over the western and southwestern parts of the country in March, with temperatures potentially reaching 40 degrees Celsius. In addition, less than usual rainfall and severe norwesters (Kalbaishakhi) are also expected.

"While this January has been recorded as the warmest, February's average temperature was 1.4 degrees Celsius higher than usual across the country," Meteorologist Abul Kalam said, adding that the warmer winter is primarily due to global warming and human-induced factors.

He said, "In Bangladesh, winter typically extends until mid-March, with lingering cold until around the 10th. However, this year that hasn't been the case."

Explaining the reasons, he said the higher winter temperatures were due to increased water vapour in the atmosphere over Bangladesh. 

"The influence of easterly winds brought warm air into the country's interior. This reduced fog density and persistence, preventing the cold from setting in," the meteorologist added.

Traditionally, January is the coldest month in Bangladesh, often experiencing one to three severe cold waves. However, this year, January went by with only a moderate one, and none in February, recording unusually warm temperatures. 

The absence of biting cold has surprised many, as winter in Bangladesh is typically marked by chilly mornings, fog and occasional cold spells.

A cold wave is officially classified when the minimum temperature remains below 10°C for three consecutive days. Cold waves are categorised into four types: Mild (8.1–10°C), Moderate (6.1–8°C), Severe (4.1–6°C), and Extreme Severe (below 4°C). 

This January, Bangladesh experienced only one moderate cold wave, centered around 10 January, when the minimum temperature dropped to 7.3°C. In February, the lowest recorded minimum temperature was 8.5°C at Srimangal on 8 and 9 February.

BMD data indicate that the average minimum temperature for January is typically 12.5°C. However, this year, the average minimum temperature in January was recorded at 13.6°C, compared to 12.7°C in January 2024.

February's mean temperature was 1.4°C above normal, while rainfall was below normal by 77% across the country.

Notably, there were no severe cold waves in January or February this year. Meteorological data show that Bangladesh experienced four severe cold waves in 2024, one in 2023 and three each in 2022 and 2021.

In March, 1-2 mild heatwaves (36-38°C) and moderate heatwaves (38-40°C) are expected. This information was shared in the BMD's long-term weather forecast for March 2025 by its director, Md Momenul Islam. 

The forecast also predicts 2-3 days of light to moderate thunderstorms with hail and one day of severe thunderstorms. Additionally, the forecast suggests less rainfall than usual, with no cyclones or low-pressure formations expected in the Bay of Bengal. 

What do global weather forecasts say about heatwave?

The World Meteorological Organization (WMO) reported that the weak La Niña event of December 2024 is expected to be short-lived. Forecasts predict a 60% chance of returning to ENSO-neutral conditions (neither El Niño nor La Niña) between March and May 2025, increasing to 70% for April- June 2025.

WMO also stated that 2024 was the warmest year on record, surpassing the Paris Agreement's 1.5°C target above pre-industrial levels for the first time. This warming trend is expected to continue into 2025.

El Niño's probability remains low, but long-term forecasts are more uncertain due to the boreal spring predictability barrier. Despite weak La Niña conditions, January 2025 was the warmest on record.

Md Rabiul Awal, a lecturer in the Department of Meteorology at DU, said that although a more intense cold wave was expected, global warming and urbanisation have reduced the perceived cold. 

He also warned that heat waves in April could intensify, especially in urban areas where the reduction of green spaces exacerbates the heat.

A recent study by Our World in Data showed that today's "cool" years are warmer than the "warm" years of the past. In 1974, the world warmed by around 0.2°C, and by 2024, temperatures had risen by 1.5°C. 

The UK Met Office predicts that 2025 could be one of the warmest years, behind 2024 and 2023. The UN's IPCC emphasises that despite La Niña's cooling effect, extreme heat remains a concern, especially in Asia, where heatwaves are intensifying and winters are weakening.