The city was hit by a squall on Sunday night, the second in two days after two rainless months.

Heavy rain, accompanied by thunder and lightning, lashed the city around 11pm. The maximum wind speed recorded at Alipore on Sunday was around 70kmph. On Saturday, the maximum wind speed was 64kmph.

The Met office had predicted thunderstorm activities across south Bengal till May 4.

“Calcutta is likely to get at least one more squall over the next 48 hours. The thunderclouds from Jharkhand stopped way short of the city on Sunday. But on Monday and Tuesday, the clouds are expected to be much stronger and reach Calcutta,” a Met official said earlier on Sunday.

Easterly winds from the Bay are dominating the districts of south Bengal. The heating of the Chhotanagpur Plateau, combined with the moisture in the easterly winds, are leading to the formation of thunderclouds that are moving towards the coastal areas.

On Sunday, the sky was partially cloudy in Calcutta almost through the day.

Saturday’s thundershowers brought rain to Calcutta after 61 days. On Friday, some parts of the city, especially in the northern fringes, receives a brief drizzle. But Saturday’s showers were widespread and uniform.

Alipore received around 14mm of rain and Dum Dum got around 30mm.

From Jharkhand, the thunderclouds came to Calcutta via Bankura, Purulia, Birbhum, West Burdwan, Howrah and Hooghly.

“All districts of south Bengal, barring Murshidabad, witnessed thunderstorm activities on Saturday,” the Met official said.

“Four separate shells over Jharkhand started moving towards Bengal on Saturday afternoon. By the time they reached Bankura, the four shells had merged into one large mass. As it came close to Calcutta, the mass became stronger because of more moisture from the Bay,” he added.

The trough of low pressure that was drawing the easterly winds now extends from Uttar Pradesh to Chhattisgarh.

Saturday’s squall cooled the city. On Sunday, the maximum temperature was around 34.5 degrees, a notch below average. The minimum temperature was around 22 degrees, three notches below normal.

The temperature was almost 40 degrees barely a week ago.

The Celsius is likely not to be oppressive for the next couple of days, Met officials said.

Air turbulence

At least 17 passengers suffered minor injuries when their Mumbai-to-Andal flight met with turbulence around 7.15pm on Sunday just as it was about to land.

The wind speed in the area was 50kmph. The passengers received head injuries when hand baggage fell on them, sources said. They were provided primary treatment and then taken to a hospital, where they were under observation.