A puja that began on a dry note is likely to end with heavy rain, the Met office said.
Ashtami was marked by a sharp spell of rain in the afternoon. The Met office has predicted a rise in the spread and intensity of the showers from Navami night. Heavy rain is almost certain on Dashami (October 2), said a Met official.
The humidity level soared on Tuesday, as did the discomfort index. Around 12.15pm, the temperature was near 33 degrees Celsius. But a 61% relative humidity meant the day felt like 40 degrees.
Across pandals, devotees clad in ethnic wear for the Ashtami anjali were soaked in sweat. The sky turned cloudy, and rain seemed inevitable. It started around 1pm. The rain was brief but sharp. For many, the rain came as a relief. But it was temporary. The weather was very uncomfortable for most of the remaining day.
The Met office recorded around 15mm of rain in Alipore. The showers were attributed to local clouds, formed by a combination of heat and humidity.
A system that will bring more rain is brewing on the Bay, the Met office said.
"An upper air cyclonic circulation is likely to emerge into the north Andaman Sea. Under its influence, a low-pressure area is likely to form over the central parts of the Bay of Bengal on Wednesday. It is likely to move west-northwestwards and intensify into a depression over the west-central and adjoining northwest Bay of Bengal around Thursday," said a Met bulletin.
Thursday is Dashami, and many idols, especially those of pujas at homes, have immersions lined up.
The Met bulletin said the system is expected to move west-northwest and hit land somewhere between the south Odisha and the north Andhra coast in the early hours of October 3 (Friday).
The next few days are likely to be rainy across Bengal, with heavy rain predicted in several areas. "For Calcutta and neighbouring districts, the period between Wednesday night and Friday morning will see the maximum impact of the system," said a Met official.
"There is an 80 to 90 per cent possibility of heavy rain in Calcutta on October 2 (Dashami)," the Met official said.
In the neighbouring South 24-Parganas, Howrah and East and West Midnapore, there is a warning for very heavy rain on Dashami.
A previous system on the Bay followed a similar pattern — a low-pressure system intensified into a depression that hit land near the sea resort of Gopalpur early on September 27 (Sashthi). It was too far from Bengal to have any significant impact.
This system is also likely to hit land between south Odisha and north Andhra. But there is a strong possibility of convergence of rain-bearing clouds to the north of the system.
Bengal will be to the north of the system when it is over the Bay of Bengal and for a while after it hits land, said a Met official. In south Bengal, Birbhum, Murshidabad, East and West Burdwan and Purulia are among the districts likely to get heavy rain on October 3 as well.
North Bengal is also likely to get "heavy to very heavy rain" between October 2 and 5.
The city was battered by torrential rain in the early hours of Tuesday. Garia got over 300mm of rain in a few hours. Ballygunge and Jodhpur Park got over 250mm. The deluge turned roads into rivers. It flooded classrooms and hospital wings and also disrupted the power supply. Swathes of Calcutta descended into darkness. At least nine people were electrocuted.