Here are 10 points on how Cyclone Amphan is moving:
The cyclone is shaped like a ring around the eye of the storm - with strong winds circulating in anti-clockwise around the eye.
It is passing mainly over North and South 24 Parganas, Midnapore, Hooghly and Kolkata.
The first impact will be when the northern parts of the ring - there will be strong winds from east to west.
The wind speed will be 155-185km/hour in the 24 Parganas and about 110-120km/hour in Kolkata.
Then as the storm moves northwards - after about 30-60 minutes of strong west to east winds - the eye of the storm will pass over each area. When the eye covers an area the winds will die down and there may even be blue skies.
Do not go out or think the storm is over because then, 30-45 minutes later the eye of the storm will pass northward and the southern part of the ring of the storm will hit the area.
The winds are now west to east and the speed will once again be as high as earlier. This will last for another 30-45 minutes.
When it hits the coast lines, the waves will be up to 4-5 metres in the 24 Parganas and 3-4 metres in Midnapore.
The waves will carry on up the rivers and the impact could be as far as 10-15 km inland.
The other worry is the strong winds carry projectiles which can be deadly and can damage anything in their way - so it's crucial to stay indoors.