Last night’s thunderstorm dragged the Celsius several degrees down in the city.

From 39.4 degrees Celsius on Sunday, the maximum temperature dropped to 35.2 degrees on Tuesday.

The morning was pleasant after a spell of powerful gusts of wind followed by uniform rain the night before. But as the day progressed, the high humidity quotient ensured that people felt uncomfortable the moment they stepped out in the open.

More such spells are expected across the state in the coming days, the Met office has said. In Calcutta, there is a possibility of a squall on Wednesday as well as Thursday, according to the forecast.

Far from the east coast, off the Andaman and Nicobar Islands, a cyclonic circulation has taken shape, said an IMD report.

“An upper-air cyclonic circulation lay over the Andaman Sea between 1.5km and 7.6km above mean sea level tilting southwestwards,” said the report.

For the next few days, Met radars will pay detailed attention to the system.

The month of May offers the best climatological conditions for a system on the Bay to intensify into powerful tropical cyclones, often barrelling towards the eastern coastline of India. Many systems, however, also fizzle out before causing any damage on land.

The system propelled southwest monsoon to the Nicobar islands on Tuesday, a week in advance.

“Southwest monsoon has advanced into some parts of south Bay of Bengal, south Andaman Sea, Nicobar Islands and some parts of north Andaman Sea today,” said a Met bulletin. The islands have been receiving light to moderate rainfall.

The usual date of monsoon’s arrival in south Bengal is around June 10.

The Met office is yet to announce any official alert about the cyclonic circulation.

“There are many factors to take into account. It is still too early to say anything,” said an official.

With no such constraints, social media was full of posts about the “imminent cyclone” and even its path.

For the next few days, hot days with the occasional thunderstorm are in store for south Bengal, said the Met office in Alipore.

“An upper air cyclonic circulation lies over East Uttar Pradesh and adjoining Bihar at 0.9km above mean sea level. A trough runs from above cyclonic circulation over East Uttar Pradesh and adjoining Bihar to south Odisha across Chhattisgarh...,” a Met bulletin said.

The heat absorbed by the earth and the moisture fed into the system by these two systems will together help create thunderclouds. The clouds will move towards the coast, getting stronger, heavier and triggering rains along the way.

In north Bengal, the rain is expected to be heavier, said Met officials.