A fresh wet spell is headed to south Bengal, the Met office has said.

Calcutta has been getting occasional showers in between hot spells. The intensity and spread of the rain are likely to rise in the coming days.

A bulletin issued on Tuesday did not include Calcutta on the list of probables, but heavy rain is not ruled out over the weekend, said a Met official.

An anticipated shift in the position of the monsoon trough has prompted the Met forecast. The trough is now passing through south Odisha and north Andhra — where a strong weather system persists — into the Bay of Bengal. The monsoon trough is south of its usual position. In the coming days, the trough is tipped to rise and make its way through south Bengal, said the official.

A low-pressure area over the Bay intensified into a depression as it hit land in south Odisha early on Tuesday. But the system, which is tipped to weaken into a well-marked low-pressure system by Wednesday, does not have a direct impact on south Bengal, the official said.

“The convergence of the rain-bearing clouds is happening in south Odisha, north Andhra Pradesh and parts of peninsular India. Scattered clouds are causing sporadic rain in and around Calcutta,” the official said.

The sky was sunny and cloudy in phases till Tuesday afternoon, after which it remained mostly cloudy. More than one spell of rain was reported from most places in the city.

“The intensity of the showers is expected to go up between August 22 and 24,” said H.R. Biswas, head of the weather section of the Regional Meteorological Centre in Alipore.

A well-marked low-pressure area on Monday morning concentrated into a depression in the afternoon. It crossed the south Odisha coast close to Gopalpur early on Tuesday, a Met bulletin said. Around 8.30am on Tuesday, it was over south interior of Odisha.

The monsoon trough now passes through Diu, Surat (Gujarat), Nandurbar (Maharashtra), Amravati (Maharashtra), the centre of the depression over south interior Odisha, and thence east southeastward into the east central Bay of Bengal.

“Extremely heavy rainfall is likely in Mumbai, parts of Gujarat, central Madhya Pradesh, south Odisha, Telangana and Andhra Pradesh over the next couple of days. After that, the trough will move up,” said a Met official.