A cloud mass drifted from the western districts of Bengal and triggered a squall that brought sporadic rain in Calcutta and some other districts for the first time this summer on Sunday evening, dragging the temperature down and bringing some relief.

Some of the western districts got hailstorms. In and around Calcutta the wind speed was around 40 km per hour, said Met officials.

The first half of Sunday was scorching in Calcutta. But the evening gave way to occasional lightning and gusts of winds.

The mercury had been hovering close to 40 degrees over the past few days. But on Sunday evening, the temperature was dragged down because of the rain.

The temperature at 7.30pm was around 27 degrees Celsius, a staggering nine degrees below the day’s maximum — 36.9. Over the past few days, the temperature was around 30 degrees at 7.30am.

On Sunday, the rain bearing clouds had formed over parts of Bihar. They reached Bengal via West Midnapore and Birbhum, said a Met official.

“Rain-bearing clouds from Birbhum drifted towards Calcutta. They grew stronger by feeding off the moisture flowing from the Bay of Bengal,” said a Met official. “There is very little chance of rain over the next couple of days.”

The city had been reeling under a hot spell. The weather became pleasant once Sunday’s thundershowers started at sundown.

Most districts of south Bengal got showers on Sunday. But districts like Birbhum, West and East Midnapore, and North and South 24-Parganas were wetter than the rest of south Bengal.

Conditions in late March and early April are at times ripe for squalls and Nor’westers in south Bengal, but the city this year has seen none so far.

The better part of March was marked by unusually low humidity. The humidity level is expected to go up in the coming days, said the Met official.