Why it hasn’t been that cold in the coldest month of the year

There were no severe cold waves in January this year, whereas at least one is mostly expected in this time period. The last time a similar kind of January was seen was nine years ago in 2016

 January is considered to be the coldest month of the year in Bangladesh. However, this year the severe cold was noticeably absent. Not only in Dhaka but across the country temperature remained higher than usual.

According to the Bangladesh meteorological department, there were no severe cold waves in January this year, whereas at least one is mostly expected in this time period. The last time a similar kind of January was seen was nine years ago in 2016. The average temperature this January was higher than in previous years, while fog levels were significantly lower.

Emran Hossain, a blanket, quilt and rug seller in Karwan Bazar told Prothom Alo last Thursday that he managed to sell only three quilts throughout the entire month of January as customer demand was extremely low. He remarks, “Why would people buy these? It’s not even proper winter.”

The reduced cold has had several negative impacts on agriculture, the spread of viral diseases and the economy. Experts warn that a milder winter is conducive to the spread of dengue fever, affects the production of crops such as wheat, potatoes and mustard which reduces sales in winter-related business.

In major cities, including Dhaka, warmer winter temperature lead to increased use of electric fans and air conditioners in offices and institutions. This, in turn, raises the demand for electricity, increasing fuel consumption for power generation and putting pressure on foreign currency reserves due to higher energy imports.

Most importantly, such a decline in winter temperatures signals ongoing climate change, which may lead to various long-term crises.

Average minimum temperature for January is typically 12.5˚ Celsius. However, this year, the average minimum temperature in January was recorded at 13.6˚ Celsius

Warmer conditions in coldest months

The intensity of winter can be measured in two ways- 1) through perceptionand 2) through temperature. If the difference between the minimum and the maximum temperature remains at or below 10˚ Celsius, the perceived cold increases. During this January, this temperature dropped below 10˚ Celsius for only three days (from January 2 to 4). 

A cold wave is officially classified when the minimum temperature remains below 10˚ Celsius for three consecutive days. Cold waves are further categorized into four types- 1) Mild: 8.1˚ Celsius to 10˚ Celsius 2) Moderate: 6.1˚ Celsius to 8˚ Celsius 3) Severe: 4.1˚ Celsius to 6˚ Celsius 4) Extreme Severe: below 4˚ Celsius. This January, Bangladesh experienced only one moderate cold wave, centered around January 10, when the minimum temperature dropped to 7.3˚ Celsius.

According to Bangladesh Meteorological department, the average minimum temperature for January is typically 12.5˚ Celsius. However, this year, the average minimum temperature in January was recorded at 13.6˚ Celsius compared to 12.7˚ Celsius in January 2024.

Notably, there was no occurrence of a severe cold wave in January this year. Meteorological data indicate that Bangladesh experienced four severe cold waves in 2024, one in 2023 and three each in 2022 and 2021.

Additionally, dense and prolonged fog was significantly less frequent this January. Continuous fog was observed for only three days. In contrast, the meteorological department reports that in January of the previous year and the five years prior, dense and prolonged fog persisted for at least seven days. Extremely dense fog reduces visibility up to 45 meters, while dense fog allows visibility up to 180 meters. This year, visibility was significantly higher than these levels.

Meteorologist Muhammad Abul Kalam Mallik told ProthomAlo that the reduced prevalence of fog during the day contributed to a lower perception of cold.

Four reasons for a less cold winter

The Bangladesh Meteorological Department monitors weather and climate data from global organizations. One such organization is the European Centre for Medium-Range Weather Forecasts (ECMWF). On 29 January noon, ECMWF reported that the moisture content in Bangladesh’s air was 68%.

Meteorologist Muhammad Abul Kalam Mallik stated that, typically, during this time of the year, the moisture level in the air does not exceed 20%. However, throughout January, there was an excessive presence of moisture in the atmosphere, which contributed to the lack of usual winter conditions. He explained that moisture in different atmospheric layers retains solar heat, thereby obstructing the flow of cold air from the upper layers of the atmosphere.

Additionally, meteorologists have identified three other key reasons for the reduced winter intensity: 1) Absence of high-pressure system 2) Lack of thundercloud formation 3) Neutral position of the Indian Ocean Dipole (IOD)

High pressure system occurs when the air pressure in a specific region is higher than in surrounding areas. When such a system dominates a region, descending air currents intensify cold conditions. This year, the absence of a dominant high-pressure system significantly contributed to the deviation from typical January winter characteristics, as observed by meteorologists.

This year, due to the Western Low Pressure system, the formation of the thunderclouds has been significantly lower. According to meteorologists, thunderclouds contribute to rainfall, which enhances cooling effects. However, this year, the absence of such rainfall has led to reduced winter intensity.

Additionally, the Indian Ocean Dipole (IOD), which refers to an irregular oscillation of sea surface temperatures, has remained in a neutral phase. The IOD has three phases- positive, negative and neutral. When in a neutral state, temperatures tend to rise, further contributing to the milder winter.

Notably, not only January but also December experienced   higher-than-usual temperatures. In December, the overall temperature in Bangladesh was 0.7˚ Celsius above normal. The weather forecast for December had predicted one or two moderate to severe cold waves, but in reality, the country experienced only two mild and one moderate cold wave.

Md. Bazlur Rashid, Senior Meteorologist at the Bangladesh meteorological department told Prothom Alo that the actual winter conditions did not align with international climate models. He attributed the reduced cold to various global climate activities influencing the weather patterns.I

If winter intensity and duration continue to decline, there is a heightened risk of increased dengue outbreaks, as the Aedes mosquito population thrives in warmer conditions.
Dr. Mustuq Husain, public health expert

Is it the impact of global warming?

According to the data from the World Meteorological Organization (WMO), the year 2024 was the warmest on record globally. The organisation’s analysis indicates that last year, global temperature were 1.55 degree Celsius higher than pre-industrial levels. Additionally, in 2024, the combined temperature of the Earth’s surface and oceans was 1.29 degree Celsius above average, the highest recorded since 1850.

In Bangladesh, the average temperature has been rising for nearly two decades. Professor AKM Saiful Islam from the department of Water and Flood Management of Bangladesh University of Engineering and Technology (BUET), told Prothom Alo that several studies suggest increasing temperature in tropical countries. One visible impact of this trend is the shrinking duration and the intensity of winter, which is already occurring in Bangladesh. He further noted that this trend is likely to intensify in the future.

What are the impacts?

Dr. Mustuq Husain, a public health expert, emphasized that colder temperatures naturally limit the spread of Aedes mosquitoes, the primary carriers of the dengue virus. In an interview with Prothom Alo, he stated that if winter intensity and duration continue to decline, there is a heightened risk of increased dengue outbreaks, as the Aedes mosquito population thrives in warmer conditions.

Shawkat Osman, Director of Crop Production Division at the Department of Agricultural Extension (DAE), explained the consequences of insufficient winter temperatures on crop cultivation. He highlighted that lower temperatures are crucial for flowering in crops such as wheat, potatoes and mustard. A lack of adequate winter conditions could reduce flowering, ultimately affecting crop yields. He further added, that heat-resistant wheat varieties have been developed to adapt to rising temperatures. However, similar adaptions are not yet available for potatoes and mustard, making these crops particularly vulnerable to potential losses this season.