The India Meteorological Department (IMD) has issued a red alert for the Mumbai Metropolitan Region, Pune, Nashik and some other parts of Maharashtra for Wednesday.
The red alert was issued for the second consecutive day.
Rains have been lashing Mumbai and adjoining districts since Tuesday night.
'The red alert of extremely heavy rainfall at isolated places has been issued for Wednesday. The probability of it is very likely, which means it could actualise up to 75 per cent,' an IMD official said in Mumbai.
The alert was issued for Mumbai, Thane, Palghar, Raigad, Pune, Ahmednagar and Nashik districts, he said.
While the warning for Mumbai is only for Wednesday, that for Thane, Palghar and Nashik is for Wednesday and Thursday, the official said.
Extremely heavy rainfall is defined as a rainfall of above 204.4 mm in 24 hours, he said.
"The south and north Maharashtra coast would receive squally weather with wind speed reaching 50-60 kilometre per hour on 4th, 5th and 6th August," the IMD official said.
Mumbai, which was lashed by rain all night, received less intense showers during the day.
Several areas of the metropolis had received more than 200 mm rain between midnight to Tuesday morning.
"Highest precipitation was reported at Borivali weather station (in north Mumbai) at 30.6 mm from 8.30 in the morning till 5.30 pm," the official said.
Other areas which received heavy showers during the day were Bandra (26 mm), Powai and Charkop (24 mm each). The rainfall was 8.6 mm in Colaba (south Mumbai) and 9.4 mm at Dadar, the IMD data showed.