Woe for seasonal crops, vegetables as winter comes late 

Roughly eleven days before Poush, the first month of winter, the first chills should already have been felt by this time, but the summer heat still hangs on, taking a toll on winter crops and vegetables. 

"For wheat production, a temperature range of 18-22 degrees Celsius is most suitable. Wheat requires ample daylight and intense cold at night. However, the current weather pattern and the forecast of milder winter will not be favourable for good wheat production," said Dr Md Abdul Hakim, principal scientific officer at the Bangladesh Wheat and Maize Research Institute.

He said wheat yield has two stages: the growth stage of the plant and the fruiting stage.

"Fluctuating temperatures during the growth stage are not a problem, but higher temperatures during the fruiting stage will reduce the yield," he added.

Dr Md Majharul Anwar, chief scientific officer of the Bangladesh Agricultural Research Institute, said, "During winter, we have crops like potatoes, various vegetables, and mustard, among others. These crops require sufficient cold.

"Higher cold intensity increases production, while less cold affects it negatively."

Majharul also said the duration of winter has been decreasing for several years now, impacting the yield.

"We are working on developing varieties adapted to these changing weather conditions to maintain yields," he added.

What it means for Dhaka people 

Well into the winter season, Dhaka residents still need to turn their ceiling fans on. Warm clothes and blankets remain unused in the closet, gathering cobwebs.

The Meteorological Department has said the winter temperature is expected to be slightly higher this year, owing to El Nino, the periodic warming of central Pacific Ocean waters.

"However, there is a possibility of one or two mild or moderate cold waves at the end of this month," says Dr Muhammad Abul Kalam Mallik, meteorologist of the Bangladesh Meteorological Department.

December usually arrives with cold wind flowing from the north and northern Bangladesh experiences the most temperature drops.

But this year, even the northerners are not feeling the cold.

There were, however, small signs of the onset of winter since the beginning of Agrahayan – the second month of Hemanta – in November.

In previous years, the arrival of winter used to be well-established by this time.

The monthly weather forecast of the Met Department, published on 3 December, also says winter will be coming slightly later compared to the previous years.

The forecast states that the temperature during the day and night this month might be slightly higher than usual.

On Tuesday, the weather forecast predicted the highest average temperature in Dhaka to be 30.8 degrees Celsius and the lowest average temperature to be 23 degrees.

"To feel the intense cold, one has to wait until the end of December," the monthly forecast says.

Meteorologists say the average night temperature in December was 14.2 degrees Celsius over the past 30 years.

A 10-15% increase or decrease in this temperature is considered normal. But if the change is 20-30% or more, it is considered slightly above normal, they say.

Winter might be late permanently

Although the winter period is generally considered from December to February in Bangladesh, this period is gradually changing.

According to meteorologists, climate change and global warming, among other reasons, are causing changes in this time frame.

Analysing the temperature data for November from the Met Department, it was found that the highest temperature in Narayanganj was 36 degrees on 1 November, and the lowest in Tetulia was 13.8 degrees Celsius on 27 November. 

This month, the country's highest temperature was 1.2 degrees higher, and the lowest 1 degree lower than usual.

The average temperature across the country was 1.1 degrees Celsius higher.

According to the department's data, this year's rainfall was also less than usual under the influence of El Nino. There was also record-low rainfall in June and July.

Even though there was more rain in August and September, it was still slightly less than usual.

Meteorologists note that a certain level of elevation in the Pacific Ocean region creates El Nino. This is why this year has seen the highest global temperature on record.

The influence of El Nino reduces the speed of east-to-west flowing winds. The rate of evaporation on the sea surface decreases, reducing the amount of water vapour in the air.

When the amount of water vapour decreases, it has less impact on lowering the temperature. It also plays a role in reducing rainfall.