The nip in the air at night is not a passing draught, for the North Wind blows early this season.
As the minimum temperature dropped to 18.2 degrees Celsius on Tuesday ' two degrees below normal ' weather officials rummaged records to ascertain when early November had last been so chilly.
Met officials said on Tuesday that the weather could continue to remain cool for the next few days but did not rule out the possibility of temperatures rising marginally before winter officially sets in on December 15.
The reason for the present chill factor is clear ' the prevailing weather conditions are a perfect precursor to winter. The three primary conditions for a season change are all in place, pointed out weather officials.
For one, the North Wind is blowing unhindered from Uttaranchal and the Himalayan ranges as the sky is clear. Also, there is no low pressure or depression over the Bay of Bengal that could lead to cyclones and heavy rains.
Finally, the moisture content in the air is dwindling (evident from the drying up of skin and lips).
'This is very unusual. Such weather conditions do not occur till around the end of November,' said R.N. Goldar, former deputy director-general of meteorology at the Alipore weather office.
Director of the weather section at the regional meteorological centre in Alipore, K. K. Chakraborty, warned that the weather could still be unpredictable. 'This cool and pleasant weather is expected to continue for the next two or three days. But there may always be a change in the wind pattern or a depression may develop over the Bay of Bengal,' said Chakraborty.
A low pressure has already formed over the Arabian Sea and it could well influence the wind pattern over Calcutta in the near future.
CESC officials said on Tuesday that the demand for power had also dropped by about 120 MW during peak evening hours.
'This is mainly because fans and air-conditioners are not being switched on. Every year, as winter approaches, we experience a drop in demand. But this year we feel the drop has come quite early,' said Satya Sundar Sinha, chief engineer (distribution), CESC.
There has, in fact, been a nip in the air from the Pujas. 'A decline in the minimum humidity level in the air has led to a steady drop in the minimum temperature,' said an official at the Alipore weather bureau.
Terming the dip in minimum temperature to 18 degrees so early in November as 'unusual', he added: 'If the present conditions prevail, we will find winter at our doorstep sooner than expected and we may have to slip on a sweater well before December is here.'