Heavy rains pounded Mumbai on Tuesday, bringing traffic to a standstill and inundating low-lying areas.
The regional weather officer has predicted heavy to very heavy rainfall for the next three days.
Eknath Shinde, Maharashtra state’s new Chief Minister, said personnel from the National Disaster Response Force had been sent to take people from at-risk areas to safer places.
TV footage showed gridlock across India's commercial centre as roads were flooded. Many train stations remained inundated, forcing commuters to wade through knee-deep water.
A subway in Andheri, west Mumbai, was closed after it became waterlogged. The upscale area of Colaba recorded 117 millimetres of rainfall in the past 24 hours.
The India Meteorological Department issued an orange alert — a warning for heavy rainfall — in coastal regions of the state and neighbouring Karnataka and Kerala for the coming days.
“Widespread rainfall with thunderstorm/lightning very likely over Marathwada and North Interior Karnataka during next 5 days ...”, the agency said.
The weather office has also predicted heavy rains in Himalayan Kashmir, Punjab, Uttarakhand and the capital, Delhi.
The heavy rains come amid a monsoon that is covering the country this week.
The monsoon usually enters India's mainland from Kerala around June 1 and then gradually moves north-west, covering the entire subcontinent over the next three months.
The country receives about 75 per cent of its rainfall during this period.
India’s agriculture depends heavily on the monsoon as it irrigates more than half of the crop-growing areas. The amount of rainfall determines not just agricultural output but also the country's economy and trade.
Although the rains came as a relief from a prolonged, record-breaking heatwave, it has also caused landslides and flooding.
In north-eastern Assam state, nearly 200 people have been killed in flooding and landslides since May.
As many as 47 people, including soldiers, were killed when a landslide triggered by heavy rain collapsed a railway unit that was being built in neighbouring Manipur state earlier this week.