The city got around 500mm of rain in May, close to four times its usual quota.

Calcutta’s normal May rainfall average is around 130mm, said a Met official. But this time, between May 1 and 31, the Met office recorded 500.7mm of rain in Alipore. It translates to a 285 per cent surplus.

The huge surplus was caused by at least four days of heavy rain in May, including the downpour caused by Cyclone Remal, after an unusually hot and dry April.

The monsoon has already set foot in north Bengal. It reached north Bengal on May 31, ahead of its usual arrival date of June 5.

The wind patterns are not favourable for its onset in south Bengal, including Calcutta, for the next couple of days, the Met office said. But scattered thunderstorms are expected in the city in the run-up to the arrival of the monsoon, said a Met official.

“The monsoon is not likely to set foot in Bengal in the next two to three days. But rain is expected, in the form of scattered thunderstorms,” said the official.

Heavy rain on Thursday (May 30) night brought relief from the unusually sweaty conditions. A Met official called them “pre-monsoon thundershowers”.

The Met office recorded around 65mm of rain in Alipore between 8.30pm on Thursday and 8.30am on Friday. In Met parlance, 60mm or more rain in 24 hours translates to heavy rain.

The rain was triggered by clouds that came from Jharkhand. “As the clouds moved towards the coast, they caused rain in the districts as well,” said the official.

In 24 hours between May 26 and 27, Calcutta was battered by some of the heaviest rain it had seen in the past few years as Cyclone Remal hit land.
The storm landed on the night of May 26, in a pocket of the Sunderbans in Bangladesh.

In Calcutta (Alipore), it caused around 190mm of rain.

The Met office recorded 72mm of rain in Alipore on May 22 — officially between 8.30am and 8.30pm, but technically, in just two hours in the afternoon.

A cyclonic circulation over Bangladesh and a trough from northwest Rajasthan to Bangladesh teamed up to bring the rain.

The systems were aided by strong moisture flow from the Bay of Bengal.

Before that, the city had received around 70mm of rain in 24 hours between the evening of May 6 and 7. But in terms of intensity, Wednesday’s rain was the strongest so far this season.

A thunderstorm brought relief to a city scalded by one of the most brutal and lengthy heat assaults in years.

The storm brought the only proper rain that the city has got in almost 50 days. Between March 20 evening and March 21 evening, the city had received around 20mm of rain. April — apart from being unusually hot — was exceptionally dry as well. All that the city got was a drizzle — 0.5mm in Alipore — on April 7.