The coming weekend is likely to be rainy in Calcutta. How rainy it will be depends on how an imminent Bay system shapes up.

In Calcutta, the Celsius rose marginally on Monday. The maximum temperature was 34.2 degrees, almost two degrees warmer than usual. Many felt the conditions were more sweaty than in the past few days.

“The upper air cyclonic circulation over south Andaman Sea and adjoining southeast Bay of Bengal persisted and extended upto 5.8km above mean sea level. Under its influence, a low pressure area is likely to form over southeast Bay of Bengal during the next 24 hours,” said a Met bulletin on Monday.

“It is likely to move west-northwestwards and intensify further into a depression over central parts of the south Bay of Bengal and adjoining west-central Bay of Bengal during the subsequent 48 hours,” it added.

October and November mark the post-monsoon cyclone season. Ideal sea-surface temperature is among the factors that help a tropical storm gain momentum. In October last year, Cyclone Dana made landfall in Odisha, causing heavy rain in Calcutta and neighbouring areas.

On Monday, the Met office said it was still too early to predict if this system would intensify further after turning into a depression. A depression usually turns into a deep depression before intensifying into a cyclone.

A seven-day forecast issued by the Alipore Met office has predicted rain across Bengal between October 24 and 26. South Bengal is expected to be rainier than the north. Calcutta is likely to get some rain.

“The wind pattern will change. Southerly winds from the Bay will be dominant later this weekend. The coastal areas of South and North 24-Parganas and East Midnapore will be more affected than other districts. How strong the showers are will depend on the Bay system,” said a Met official.