The city spent yet another sunless and rainy day, while the Met forecast predicted more showers.

Some parts of the city received a sharp spell of rain in the early hours of the day. It was accompanied by incessant streaks of lightning.

Between 5.30pm on Tuesday and 5.30pm on Wednesday, the Met office recorded close to 40mm of rain in Alipore. A bulk of it came down between 4am and 6.30am.

The rest of the day saw intermittent showers. The sun stayed hidden, like it has been the past few days.

Chief minister Mamata Banerjee led a march from College Square to Esplanade on Wednesday afternoon. The rally was drenched in rain. "Those who got wet, please take care and have medicines. Take precautions. There is no need to worry," Mamata told the marchers.

The Met office had predicted cloudy conditions for Wednesday, but the sun was expected to make at least brief appearances, which did not happen.

"The monsoon trough is more than active. A system, though depleted, is still at play. The trough is constantly feeding clouds into south Bengal," said a Met official in Alipore.

"Localised convections may lead to formidable rain in some places. Like Calcutta got one early on Wednesday, Asansol got later in the day, recording 50mm of rain," he said.

In Met parlance, 60mm of rain in 24 hours qualifies as heavy.

A well-marked low-pressure area was over southwest Bihar and adjoining east Uttar Pradesh on Wednesday morning, said a Met bulletin. It is likely to move west-northwestwards across southwest Bihar and east Uttar Pradesh. The monsoon trough passes through the centre of the low-pressure area, Purulia, Contai, and then into the northeast Bay of Bengal, the bulletin said.

"A cloudy sky and light to moderate rainfall" is the forecast for Calcutta for Thursday.