The maximum temperature on Sunday was 23.4 degrees, two notches below normal, for the second day on the trot. The minimum was 14 degrees. The low day temperature added bite to the chill.

On January 13, the city had seen the maximum temperature dipping to 23.1 degrees. But the city had been under a warm spell back then, triggered by a strong Western Disturbance that had stalled the flow of cold north-westerly winds.

With the north-westerly winds back on track and the minimum temperature in the normal range, the low day temperature on Sunday made its effect felt. Winds from the Northeast and Bangladesh have been causing some cloud formation and a blanket of fog in Calcutta, keeping the sun from shining brightly throughout the day. As a result, the day temperature has been lower than usual, said a Met official.

The Met office had forecast a marginal rise in the Celsius from Monday. But a trough of low pressure over Bengal that was tipped to trigger the rise has not yet formed, said a Met official.

“The trough is expected to take shape by Tuesday. Till then, the mercury will be under check in Calcutta, in the range of 14 degrees,” he added.

Once the trough takes shape, it is expected to send easterly winds to Andhra Pradesh, Chhattisgarh, Madhya Pradesh and parts of Uttar Pradesh. The moisture-laden winds will stall the flow of the cold north-westerly winds and push the mercury upwards in Calcutta.

“The minimum temperature will be in the range of 17 to 18 degrees in Calcutta. But the rise will be temporary…. From January 21, the mercury will again start plunging in Calcutta,” said the Met official.