A hint of chill, missing altogether in November so far, is on its way, the Met office has said.

After consistently staying several notches above normal for half of the month, the minimum temperature is set to slide from Saturday, according to the forecast.

The minimum temperature on Thursday was 22.1 degrees Celsius, almost two notches above normal. The usual minimum temperature for November — on the basis of Met readings compiled over the past 30 years — in Alipore is around 20 degrees.

So far this November, the lowest minimum temperature recorded in Alipore was 21.5 degrees on Wednesday. Before that, the lowest was 21.8 degrees on November 10.

“The minimum temperature is expected to dip to 20 degrees on Friday. Over the next three to four days, the minimum temperature is expected to slide three to four degrees,” said H.R. Biswas, head of the weather section at the Regional Meteorological Centre in Alipore.

The first half of November was warmer than usual because of the flow of southeasterly and southwesterly winds, from the Bay, into coastal south Bengal. The moisture-laden winds put a spanner in the works of the northwesterly winds, the usual agent of chill in mainland India.

“But now, the wind pattern is changing. Dry northwesterly winds are set to dominate the atmosphere, even in the lower level. The weather will be seasonal. The nights and early mornings will have a hint of chill,” said Biswas.

The extended range forecast for the next two weeks, issued by the India Meteorological Department headquarters in Delhi, said a “gradual fall in minimum temperatures by 2-4°C was very likely over East India during next one week”.

Early mornings will be partially foggy in Calcutta, the Met office said.

Unlike the monsoon, there is no official announcement from the Met office on the onset of winter in Calcutta. But three to four days without rain and the minimum temperature of less than 15 degrees are usually the markers of the onset of winter.