The Celsius dropped below 20 degrees on Friday for the first time this year since March as winds from the north made their presence felt in the city.

The cool phase will continue for the next few days because of favourable conditions in northern India, the weather department said.

Friday’s minimum temperature was 19.8 degrees Celsius — two notches below normal.

The last time the city had recorded a sub-20 degrees temperature was on March 22, when the mercury had dipped to 19.2 degrees, according to the Met records.

Winter is still some distance away, the Met office said. Unlike the monsoon, the weather office in Alipore does not announce the onset of winter. There are, however, certain parameters that mark the arrival of the season.

One such parameter is that the minimum temperature has to be 15 degrees or less for at least four days at a stretch.

“The sky is clear. The dry and cold north-westerly winds are getting an unobstructed access into the city. The minimum temperature is likely to remain in the range of 19 degrees over the next couple of days,” said a Met official.

Snowfall in the upper reaches of the country had triggered the flow of north-westerly winds into the city at the start of this week. The cold phase in Calcutta is expected to be temporarily halted from Tuesday, when a cyclonic circulation over the Bay is tipped to inject moisture into the city.