Here are the top 10 updates in this big story:
Private weather forecast agency Skymet said with dense low clouds over Mumbai, visibility in the city has reduced to 500 metres. Rains will intensify in the evening and wind speed is likely to exceed 50 km per hour.
"Monsoon has reached Goa and it can take up to 72 hours for it to reach Mumbai. There will be heavy rain on June 9," met office director Ajay Kumar told NDTV. The met department has advised people not to step out of home on Saturday and Sunday unless necessary.
Despite the precautionary measures taken by the Mumbai civic body, waist-deep water was observed in some areas of the city. Flooded roads have been reported from Dadar, Parel, Cuff Parade, Bandra, Borivali and Andheri.
The waterlogging has hit rail services, with the local trains running around 20 minutes late. Several trains were reportedly forced to wait as power supply was disrupted as well.
A Jet Airways flight from London to Mumbai was diverted to Ahmedabad airport due to heavy rains. Eight other flights of different airlines were diverted to other airports on account of congestion at Mumbai.
In the evening, navy personnel will be posted in Colaba, Worli, Ghatkopar, Trombay, Malad for flood rescue, reported news agency Press Trust of India.
Officers have been asked to keep schools open at all times for shelter during possible flooding.
The Mumbai civic body has taken a number of precautionary steps that include cancellation of leaves of senior officials over Saturday and Sunday.
The usual date for onset of monsoons in Mumbai is June 10, This year, met office had forecast early rains.
The monsoon reached the Goa and Konkan coast today. Over the weekend, rain is expected in Gujarat, Karnataka, Goa, West Bengal and Odisha. Fishermen have been asked not to venture to sea and tourists have been asked to stay away from coastal areas. The emergency helpline numbers for Mumbai are: BMC Disaster Management: 1916, 22694725