An active southwest monsoon over sub-Himalayan West Bengal is set to bring heavy rainfall to the region over the next week, the India Meteorological Department (IMD) said on Saturday.

Thunderstorm activity is also expected across southern districts of the state, where the monsoon has already advanced, the weather office said.

In Kolkata, conditions are likely to turn comparatively cooler, offering relief to residents after days of high daytime temperatures and persistent humidity that made conditions uncomfortable.

According to the IMD, widespread rainfall is expected over the sub-Himalayan districts of Darjeeling, Kalimpong, Jalpaiguri, Alipurduar and Cooch Behar over the next seven days, with the possibility of “very heavy rainfall” at isolated locations on June 16 and 17.

In south Bengal, thunderstorms are likely to be more intense in Purba and Paschim Bardhaman, Birbhum, Murshidabad and Nadia districts, it added.

The Met office also noted that none of the districts in the state recorded any rainfall in the 24 hours ending 8:30 am on Saturday.