• Maximum temperature on May 9: 30.4 degrees Celsius
• Maximum temperature on May 16: 37 degrees Celsius (RealFeel: 45 degrees)

The wet spell is gone and the Celsius is northbound in Calcutta again.

There is no immediate respite in sight from the heat. To make things worse, the heat this time is accompanied by a known accomplice, humidity.

During the recent spell of heatwave, the heat was dry on most days. This time, the conditions will be sweaty, said a Met official.

The Met office said on Thursday evening that a low-pressure area is likely to take shape over the southeast Bay of Bengal and the adjoining Andaman Sea around May 23.

“There is a moderate probability for its further intensification into a depression over southeast Bay of Bengal and adjoining north Andaman Sea.... The system is likely to intensify further and move north-northeastwards,” said a notification from the IMD.

May has seen some of the most devastating cyclones — Amphan in 2020 and Aila in 2009 — on the Bay of Bengal.

But there is a rider. The southwest monsoon is expected to advance into the southeast Bay of Bengal on May 19. The strong monsoon currents might deter the intensification of the system, said a Met official in Calcutta.

“The monsoon flow is characterised by a high and significant vertical wind shear, which is not conducive to the intensification of a cyclone,” said Somenath Dutta, the deputy director-general of the India Meteorological Department, Calcutta.

On Thursday, the Met office recorded a maximum temperature of 36.9 degrees in Alipore. It was a notch above normal. At 29.2, the minimum was two notches above normal.

It is likely to go further up, according to the forecast.

But the key to the sultry conditions was the relative humidity. The minimum relative humidity was close to 50 per cent. It means the moisture content of the air was over 50 per cent for most of the day.

Around 2pm on Thursday, the maximum temperature was around 37 degrees, according to the website of a private forecasting agency. But the RealFeel was 45 degrees.

According to the Met forecast, the maximum temperature is likely “to rise gradually by 2-4°C during the next three days over the districts of Gangetic West Bengal”.

Some rain is expected in Calcutta on Sunday and Monday. But even if that happens, a brief spell of rain will bring only a temporary relief from the scorching conditions.