The India Meteorological Department issued a red alert for Mumbai, Thane, Pune, Raigad and Ratnagiri districts in Maharashtra for Tuesday after upgrading its earlier rain forecast from "heavy-very heavy" to "extremely heavy".
An IMD official on Monday said the "extremely heavy" forecast means Mumbai, Raigad, Thane, Pune and Ratnagiri may get more than 204.5 millimetres of rain in a period of 24 hours.
"Mumbai, Thane, Pune would receive extremely heavy rainfall in isolated places on Tuesday and Wednesday. Raigad has a similar forecast between Monday and Wednesday," he said.
"The probability of the forecast is very likely, which means 51 per cent to 75 per cent of actualisation," the official added.
Neighbouring Palghar district would get heavy to very heavy rains at a few places on Tuesday and the intensity would increase on Wednesday, the IMD said.
The rest of Maharashtra was very likely to get rain and thundershowers in isolated places during this period, the official informed.