Monday looked like a day in the monsoon, and the Met office has forecast a similarly grey sky with rain on Tuesday, too.

Thunderstorms and gusts of wind clocking up to 40km an hour are likely to accompany the rain.

The downpour is likely to go up further between Thursday and Saturday, with the maximum rain expected on Friday, an official of the India Meteorological Department (IMD) said.

A bulletin issued by the IMD alerted residents to “take shelter in a safe place during thunderstorm activity”. It asked them to “avoid taking shelter under a tree or an electric pole and to avoid contact with water bodies”.

Moisture incursion from the Bay of Bengal and a favourable wind pattern were behind Monday’s rain.

“Under its impact, light to moderate rain is expected for the next few days, accompanied by strong winds,” the official said.

The sky was cloudy since Monday morning. It rained across the city, though with varying intensity and volume.

“Monday was the first day this year when the city was overcast through the day,” said a central Calcutta resident.

The Kolkata Municipal Corporation, which measures rainfall in its drainage pumping stations, recorded maximum rain in Duttabagan in the extreme north — 59mm. Topsia in the east received 52mm rain; Ballygunge received 8mm, Chingrighata 39mm and Thanthania 29mm.

The sky will remain generally cloudy. Light to moderate rain, with lightning and thunderstorms, is likely on Tuesday.

A resident of Haldiram’s on VIP Road had to shelve her plans of coming to central Calcutta for work on Monday.

“There was knee-deep water on the service road that leads to my home,” said the resident of Koyla Vihar Abhinandan, a housing complex on VIP Road.

“One of my neighbours returned home and told me the entire road was under water,” she said.

From Thursday, Calcutta and south Bengal districts are likely to get heavy rain because of a low-pressure system that will form over the Bay of Bengal.

“The low-pressure is likely to form over the Bay of Bengal from Tuesday. It will reach Calcutta and its neighbouring districts by Wednesday, but the impact will be felt
from Thursday. We are expecting heavy rain from Thursday,” the Met office has said.

In Met parlance, up to 15.5mm rain in a 24-hour period is considered light rain. Rainfall between 15.6mm and 64.4mm is considered moderate.

And when it rains between 64.5mm to 115.5mm, the Met calls it heavy.

Several cities in India are reeling under rain and waterlogging.

Mumbai and Delhi have received heavy rain in the past few days.

Heavy rain in Delhi tore through the membrane shade at the arrival forecourt of Terminal 1 of the Indira Gandhi International Airport on Sunday morning. Trains were disrupted in Mumbai.