Winter may be just days away. The chill was felt on Monday, the coldest day of the season, with the minimum temperature dropping to 16 degrees Celsius.
The mercury had slipped from 20.5 to 18.8 degrees Celsius, a drop of 1.7 degrees between Saturday and Sunday. On Monday, the drop was sharper at 2.8 degrees as the city emerged from the effect of Cyclone Lehar and the resultant excess moisture.
The maximum temperature recorded on Monday was 28.1 degrees Celsius, normal for this time of the year, and the same as last year’s reading on this day. The minimum temperature, however, had been lower last year at 15.2 degrees Celsius.
It is likely to get colder with the minimum temperature dropping to 15 degrees Celsius on Tuesday and a notch further by Friday. “There’ll be a steady fall in temperature from now and we expect all the parameters for winter to be satisfied by Wednesday,” said Gokul Chandra Debnath, director, India Meteorological Department, Calcutta.
For winter to be declared, the maximum temperature has to be 28 degrees Celsius or below and the minimum 16 degrees or below. Also, the summation of the maximum and minimum relative humidity (RH) must be within 140 per cent and such conditions must prevail for three to four days.
The total relative humidity came down to 137 per cent on Monday with the minimum dipping below 50 per cent for the first time since Lehar. On Monday, both the maximum and minimum relative humidity fell further for the total to read 127 per cent.
“The relative humidity is vital for a chilly feeling to be experienced in Calcutta. The lesser the moisture content in the air, the more freely the cold winds from north India can blow into the city, thus reinforcing the cold,” said a weather scientist.
The only spoiler could be a low-pressure area that is expected to hit the eastern coast in Tamil Nadu later this week.
If it swerves north, it could cause moisture incursion in Bengal and lead to a rise in temperature once again.