A thunderstorm on Thursday morning brought brief respite from the searing heat that had gripped the city over the past few days.

Rainfall, however, remained negligible, with the spell mainly marked by flashes of lightning and frequent claps of thunder. The overcast sky helped pull the maximum temperature down to 32.4° Celsius, about three degrees below normal.

The rain and wind were patchy. While parts of south Calcutta received showers, areas in north Calcutta and Salt Lake remained dry. Despite the uneven rainfall, the sky stayed largely overcast through the day.

“Another spell of thunderstorm is likely in the next 24 hours,” a Met official said on Thursday afternoon.

If it occurs, daytime temperatures are expected to remain below normal on Friday as well. But there is no indication of a widespread wet spell, and conditions are likely to turn scorching again, the official added.

Thursday morning was cloudy, breezy and rainy. The Met office recorded a peak wind speed of 42kmph in Alipore around 9am.

Met officials said the showers were triggered by local clouds, resulting from a combination of heat and humidity.

Rain and wind were stronger in neighbouring districts, including North 24-Parganas, South 24-Parganas and Nadia. A second spell of thunderstorms was reported in some areas later in the day during the afternoon and evening.

Around 4.50pm, the Met office issued a warning of “severe thunderstorms” for Murshidabad, Birbhum and East Burdwan. Some parts of Birbhum also experienced hailstorms, officials said.

Summers in Calcutta are marked by hot and humid conditions, pushing up the discomfort index and leaving people sweaty for much of the day.

This year’s summer has so far been relatively less severe, but for the past few days the sun has been intense and relentless, with maximum temperatures approaching 37°.

“When humidity levels are high, sufficient heating can trigger the formation of rain-bearing thunderclouds. While there is no forecast of a sustained wet spell, adequate heat and humidity can lead to localised showers,” Met officials said.