The IMD on Wednesday said a low-pressure area is likely to form over the northwest Bay of Bengal on July 3, bringing heavy rainfall to south Bengal, while the sub-Himalayan districts are expected to get respite from the heavy downpour experienced over the past several days. A favourable wind pattern and strong moisture incursion from the Bay of Bengal are likely to trigger heavy to very heavy rainfall in some districts of south Bengal, the India Meteorological Department (IMD) said. It said heavy rainfall is likely over several south Bengal districts from July 4 to 7 due to the expected formation of the low-pressure area. Heavy to very heavy rainfall is forecast over South 24 Parganas, Purba Medinipur, Paschim Medinipur, Jhargram, Purulia and Bankura districts on July 5 and 6, it said. Sagar Island recorded the highest rainfall in the state at 13 cm in the 24 hours ending at 8.30 am on Wednesday, the IMD said. Other places that received significant rainfall during the period included Burnpur in Paschim Bardhaman (10 cm), Bankura (8 cm), and Medinipur and Dum Dum (5 cm each), according to the weather office. The intensity of rain over several places in north Bengal will decrease over the next few days, the IMD said. However, thunderstorms with gusty winds are likely over the north Bengal districts during the next few days, it said.