Alipore: A squall that clocked 80kmph, and accompanying showers, brought a much-needed reprieve to the city after soaring humidity and temperature had made conditions sultry and uncomfortable during the day.

The storm uprooted two trees in the Hastings area and on Judges Court Road in Alipore, caused flight diversions and stalled trains on the Sealdah-Budge Budge section. No injuries were reported till late on Thursday.

The last squall that hit the city - on April 17 - had claimed 11 lives in Calcutta and Howrah. The storm had clocked 98kmph that day.

This was the season's fifth squall in Calcutta. Thunderstorms are on the cards on Friday as well.

The rain started around 7.45pm and continued late into the night. By 8.30pm, many places in Calcutta received over 25mm of rainfall.

The Calcutta Municipal Corporation's drainage pumping station at Dhapa recorded 34.4mm of rain and the one at New Market, 29.5mm.

The Alipore weather office recorded 21mm till 8.30pm.

Thursday's maximum temperature was 35.1 degrees Celsius, which was normal for this time of the year. Around the time the maximum temperature was being recorded, the city's RealFeel was as high as 43 degrees Celsius.

The RealFeel, a measure of the effect of the elements on the human skin, is calculated by weather portal Accuweather.com.

"High humidity had made the weather sweaty. The minimum relative humidity, which indicates the moisture content in the air during the hottest part of the day, was 54 per cent. When the humidity crosses 45 per cent and the temperature is in the mid-30s, the condition can be very uncomfortable," a Met department official said.

The temperature was 30 degrees Celsius at 7.45pm, when the rain started. The first gust of wind - clocking 47kmph - came at 7.50pm, blowing from south-west. The wind speed reduced a little, only to increase suddenly and touch 80kmph.

By 8.15pm, the temperature had dropped to 20 degrees.

Because of the strong winds and lightning, seven Calcutta-bound flights had to be diverted to Bhubaneswar and Guwahati. Airport officials said at least 10 other flights had to hover over Calcutta for more than 30 minutes before they could land.

A passenger on an IndiGo flight from Lucknow said he was scared by the turbulence. "The flight was supposed to land at 8pm. But it was delayed by almost an hour as the plane was making rounds. There was severe turbulence and I felt scared. I could see lightning outside. This was the first time I was caught in such a situation," he said.

No flights could take off during the squall. Services resumed around 9pm, officials said.

Train services between Sealdah and Budge Budge were stalled for over 40 minutes, from 8.40pm, after an overhead wire snapped near Santoshpur station. Circular Railway services were affected, too.