A low-pressure area became stronger as it moved from Bengal to Jharkhand on Wednesday, triggering persistent showers across the state.

The Met office recorded around 12mm of rain in Alipore between 5.30pm on Tuesday and 5.30pm on Wednesday. The consistent showers and overcast conditions dragged the Celsius down.

The next few days are also likely to be rainy, said officials. The intensity of the showers will wane between Friday and Sunday. From next Monday, the intensity would rise again with a fresh system taking shape, said Met officials.

“Tuesday’s low-pressure area over southwest Bangladesh and adjoining Gangetic West Bengal moved west-northwestwards and became a well-marked low-pressure area and was over Gangetic West Bengal and neighbourhood on Wednesday morning,” said a Met official.

The Southwest monsoon was propelled into south Bengal by the system on Tuesday.

“The associated upper air cyclonic circulation extending up to 7.6km above mean sea level, tilting southwards with height, also persists. The system is likely to move slowly northwestwards across Jharkhand during the next 24 hours,” he said.

The southern fringes of Calcutta got more rain than the rest of the city. Hooghly, Purulia and Bankura also received heavy rain.

Joka and neighbouring areas received around 60mm of rain between Wednesday morning and evening. Mogra in Hooghly got 99mm; Purulia got 85mm and Bankura 71mm.

The maximum temperature in Alipore was 27.7 degrees, six notches below normal. On Tuesday, it was 28.4 degrees, more than five notches below normal. It was the lowest in almost three months. On March 22, the maximum temperature was 25.5 degrees.

Heavy to very-heavy rainfall (7-20cm) is likely in Purulia, Bankura, West Burdwan, Jhargram and West Midnapore on Thursday, according to the Met forecast. Heavy rainfall (7-11cm) is expected in East Burdwan, East Midnapore, Birbhum and South 24-Parganas. There is no warning for south Bengal from June 20 to 22.

“A low-pressure area or a cyclonic circulation is likely to form next week. It can take shape over the North Bay or on land. In south Bengal, the intensity of the showers will go up from June 23,” said H. R. Biswas, head of the weather section at the Regional Meteorological Centre in Alipore.

“The monsoon currents are active now. They will trigger rain even when there is no system,” he said.