Mumbai's dabbawalas have also suspended their services on Tuesday.
Private weather agency Skymet said Mumbai is at 'serious risk of flooding' between July 3 and 5.
Mumbai recorded over 250 mm of rain in just three hours (between midnight and 3 am), touching 305 mm by 7 am on Sunday, a meteorologist said.
The low-lying areas of Parel, Dharavi, Matunga and King's Circle in Mumbai and towns in the neighbouring Thane district, including Diva, Dombivali, Kalyan and Ambernath, were flooded due to copious rains.
The red alert was issued for the second consecutive day. Rains have been lashing Mumbai and adjoining districts since Tuesday night.
It is the highest rainfall of the season so far in 24 hours.
Heavy rains in Mumbai's Dadar area led to waterlogging, causing numerous problems to commuters.
Mumbaikars travelling to work faced a harrowing time on Tuesday morning owing to waterlogging caused by the incessant rain since Monday night.
Mumbai and its adjoining areas were lashed by heavy showers on Tuesday, causing water-logging at a number of places, including railway tracks, which slowed the movement of trains and vehicles on roads.
Thirteen teams of the National Disaster Response Force and three of the State Disaster Response Force were deployed in vulnerable districts of the state, a disaster management department report said.
Water, mats and chairs, among others things, have been arranged for commuters at these schools which are located close to railway stations, he said.
A day after heavy showers battered Mumbai, the rain intensity reduced briefly on Monday morning and picked up momentum again, leading to water-logging at some places and disrupting local train services, officials said.
Incessant rain has lashed parts of Mumbai on Tuesday morning, disrupting local train services and road traffic with water logging in several low-lying areas. The weatherman has predicted widespread rainfall in the state during the next 36 hours.
The CM said he spoke to the Mumbai Police Commissioner and was informed that traffic has been diverted at 25 places.
Heavy rains lashing Mumbai since Sunday have thrown rail, air and road traffic out of gear, with several trains and flights being cancelled. With IMD forecast of heavy rains for Tuesday, the authorities declared a holiday in the city and adjoining regions, asking people to avoid stepping out of their houses.
'It's not possible for me, or any middle class family, to purchase a new home in Mumbai.'
As part of the exercise, preventive checks at different airport functions have been carried out and the airport has ensured that diesel generator sets are in place to provide uninterrupted power supply, the MIAL said in a release.
We bring you glimpses of what Mumbai is going through.
Heavy rains threw normal life out of gear in India's financial capital, Mumbai.
Bringing in the much-needed respite from the hot and humid conditions, the monsoon arrived in Mumbai with heavy showers lashing the city Thursday night and Friday morning.
Weathermen have also predicted heavy to very heavy rainfall in the next 24 hours in the entire Konkan region, including Mumbai.
Probe found that they had opened the manhole so that the water in the area, which had entered their houses, could drain out, police said.
Eight people were killed and five injured in rain-related incidents across Maharashtra where several parts were lashed by heavy rains on Friday.
Disaster management authorities have warned about very heavy rainfall over the next 24 hours.
Maharashtra Chief Minister Eknath Shinde reviewed the rain situation on Tuesday and said over 3,500 people had been shifted to safer places from flood-prone and vulnerable spots across the state, where several districts, including Mumbai, experienced downpour.
The Indian Meteorological Department, meanwhile, warned of intense spell of 30 to 50 mm rainfall per hour with strong winds in Mumbai and suburban areas.
Mangroves absorb excess water but they are being destroyed in Mumbai in the guise of infrastructure development, city-based environmentalist Debi Goenka told PTI.
The most dramatic images of the Mumbai rains sent in by our readers.
Bharadwaj said it has not rained in Delhi in the last 3-4 days, yet still the water level in Yamuna reached 208.66 metres.
The Maharashtra government has directed all schools and colleges in the city and neighbouring Thane district to remain closed on Saturday.
I write this from Mumbai, on a day that news anchors are calling "waterlogged" and "rain drenched". A completely wasted day for the city that never sleeps, in fact. No trains, no buses, no way to leave our homes, no staff, no home delivery, no greengrocer and milkman at the door, poor TV reception, no Internet connectivity -- nothing.
Authorities issued an alert asking people not to venture out of their homes unless it was absolutely essential.
'Coronavirus is not the only emergency, and it is certainly not the only illness people can suffer from'
Streets in localities like Hindmata, Dadar, Sion, King's Circle and Wadala are waterlogged. Suburban trains were running slow when reports last came in.
Heavy rains continued to lash Mumbai and neighbouring Thane from 11 am on Monday.
