Cyclone Nisarga, that could well be one of the worst cyclones to hit the West coast of India, is just around 150 to 160 km off Mumbai.
Around noon on Wednesday, the deep depression emanating from the Arabian Sea is expected to make landfall in Alibaug in Raigad district.
The coastal Konkan region is likely to be affected badly.
"Cyclone Nisarga approaching North Maharashtra coast with a speed of 13 kmph during past 06 hours. It is 155 km south-southwest of Alibag and 200 km south-southwest of Mumbai," according to an IMD advisory issued around 7 am.
According to IMD's deputy director-general of meteorology Dr KS Hosalikar, heavy rainfall warnings for Mumbai, Thane, Raigad and Palghar are already issued in view of cyclone.
"High winds, very rough sea. Please keep watch. Take care," the weatherman tweeted.