Kolkata among 9 megacities to experience prolonged heat stress

Daytime temperatures will remain around 40 degrees Celsius for many more days to come. In the month of May, the average daytime temperature of the city was 38 degrees Celsius, which has remained constant for almost a decade. However, that trend is set to change as meteorologists have indicated that the average temperature of the day will rise to 40-41 degrees Celsius in Kolkata.

The weather forecast for the next 15 days suggests that temperature on Tuesday will be 35 degrees Celsius — which would make it the coldest day until June. From Thursday to the end of the month, the average daytime temperature will be 40 degrees Celsius.

"People often suffer under the misconception that the Nor'wester decreases daytime temperatures. However, that is true only to a certain extent. Sometimes, the temperature rises after the rain," said a meteorologist. Historical data of the city's weather conditions suggests that Kolkata recorded 43.7 degrees Celsius in May 28, 1958. The lowest was way back on May 3, 1887. The temperature that day was 18.3 degrees Celsius. The city was never as rainy in the month of May as it is now, with the total rainfall recorded at 101.7 mm while the average number of rainy days is less than six.

"The Nor'wester on Saturday afternoon lowered the temperature slightly. However, it rose again on Sunday morning. It was around 38 degrees Celsius on Sunday. The temperature remains around 26 degrees Celsius at night," another meteorologist added.

According to Skymet weather, a private weather forecaster, Kolkata has been experiencing warm weather for quite some time now. New reports have come in and they suggest that heat stress on Kolkata has been rising to quite an extent.

"As per the report published by the US journal Proceedings of the National Academy of Sciences, 350 million people across 44 mega cities in the world will go through a prolonged heat stress. Out of these, nine cities are from India including Kolkata, Bengaluru, Mumbai, Delhi, Chennai, Surat, Pune, Hyderabad and Ahmedabad," Skymet weather reported.

"Heat stress basically means that the human body is experiencing more heat than it can take. Heat stress is calculated by using the heat index which includes both humidity and air temperature," the agency added.

In India, heat waves have been increasing continuously for the past few years.

In fact, the year 2016 has been the hottest since 1901. Due to increasing temperatures, global warming and population growth, heat stress will only increase in the coming years, Skymet said.

Even if global warming is halted at Paris goals, the megacities of Karachi, Pakistan, and Kolkata, India, could face annual conditions similar to the deadly heat waves that gripped those regions in 2015.

During the 2015 heat waves in those areas, about 1,200 people died in Pakistan and more than 2,000 died in India.