It can at best be described as the harbinger of monsoon, said G C Debnath, director of the Alipore weather office. "It is only after the pre-monsoon showers do we know that the monsoon is not far behind," he added.

The Met office had earlier predicted that the monsoon would hit the city between June 5 and 10, but this has been slightly delayed and now it expects the monsoon to arrive on June 13. Monoon usually arrives in the state around June 8-10.

At present, it has advanced into parts of south-interior Karnataka, Tamil Nadu, south-west, east-central, north-west, north-east and westcentral Bay of Bengal, apart from some parts of the north-eastern states. Over the next 24 hours, sharp to heavy rainfall is expected all over the state.

The maximum temperature on Friday was 32.7 degrees Celsius, two degrees below normal, and the minimum temperature was 25.1 degrees Celsius, one degree below normal. The city recorded 11.8 mm rainfall.

Heavy rain is also likely to lash isolated places in Sikkim as well as Darjeeling, Jalpaiguri and Cooch Behar districts in another 48 hours. Thundersqualls, at a speed of 50-60 km per hour, are likely to hit isolated places across the state in 24 hours. Also, strong south-westerly winds, having a speed of 55-65 kmph, are expected. Fishermen have been warned not to venture into the sea and local cautionary signal III has been hoisted at all ports.