A cloak of cloud and intermittent showers marked Independence Day, after heavy overnight rain.

A weather tracking website of the Calcutta Municipal Corporation showed parts of the city, such as Chowbagha off the EM Bypass and Patuli, got over 100mm of rain between Wednesday morning and Thursday morning. Jora Bridge and adjoining areas got 65mm of rain.

Alipore got over 70mm of rain between Wednesday morning and Thursday afternoon, according to the Met office. In Met parlance, 60-120mm of rain in 24 hours is considered heavy rain.

Amlan Banerjee, a Jadavpur resident, had left his office in Dalhousie Square around 11pm on Wednesday. “When I boarded a cab, it was drizzling. By the time, I reached home, it was raining heavily. Around midnight, all the windows were closed but you could still hear the thud force of the showers,” he said.

But the rain was not heavy across the city. Ballygunge got around 37mm, Cossipore 17mm and Dum Dum 25mm of rain, the CMC website stated.

An active monsoon trough passing through Midnapore and then into east-central Bay of Bengal is behind the rains, the Met office said.

“The monsoon trough is drawing more moisture-laden air from the Bay of Bengal than the Arabian Sea. The next couple of days are also expected to be rainy in south Bengal and Calcutta,” said G.K. Das, director, India Meteorological Department, Calcutta.

The monsoon trough is an imaginary line joining low-pressure points across the breadth of the country.

The sun made occasional and brief appearances on Thursday. The sky was overcast for most of Thursday, bringing the Celsius down.

The maximum temperature was 30.1°C, two notches below normal. The minimum temperature was 25.7°C, a notch below normal.

The weather and a public holiday meant a surge in app cab prices. “A ride from Shyambazar to Rajabazar would cost me Rs 400, the app showed around 4pm. I kept checking multiple times over the next 30 minutes but the fare would not come down. The normal fare is under Rs 100. The expected arrival time of the car was consistently over 10 minutes,” a Shyambazar resident said.

After June and July ended on a dry note, August so far has been quite rainy. The city had received around 220mm of rain so far this month, till Wednesday. The normal August rain volume is around 345mm, a Met official said.