The mercury column would climb up in the next couple of days because of a depression over Bay of Bengal, giving respite to residents after they shivered in November.

On November 29, the mercury dipped to 10.2°C — the lowest temperature of the month in the past six years (see graphic). But the first week of December would end on a warm note.

The nights would be warmer by two to three degrees Celsius. The day temperature would not deviate much, though. Foggy condition would prevail in the city up to 8am.

Ashish Sen, the director (radar) of India Meteorological Department (IMD), told The Telegraph: “The low pressure area over the Bay of Bengal is expected to cause moisture incursion in the atmosphere over Bihar as well. There are possibilities of precipitation in Bengal and south Jharkhand, but the weather in Bihar would remain dry. The moisture incursion would trap the radiation from the earth’s surface at night, prompting rise in the night temperature. The moisture cover would also cause obstruction in the penetration of solar radiation in the daytime, but the resultant dip in the day temperature would be marginal.”

He said: “The fog would gradually intensify in the city with the advancement of the low pressure area towards Bihar. The wind speed would be around 5 to 6 kilometres per hour. It would blow from the east to the west. Such conditions would prevail in the next two-three days, after which the temperature would start dipping again.”

There was a steady dip in the minimum temperature in the city in the past few days. The minimum temperature went below 10°C for the first time this winter on Sunday (9.9° C, two degrees below normal). On Saturday, the lowest was 11°C, one degree below normal. The minimum temperature on Friday was 10.8°C.

Deliberating on the weather conditions after the depression weakens, Sen said: “The next phase of cooling is expected to start from December 7. It would be accompanied by formation of dense fog in the morning up to 9am. The wind chill factor would be come into play from December 15.”

Sen claimed that this winter was similar to the one of 2009, when the average minimum temperature at this time of the year was around 10°C.

“The winter of 2010 was comparatively warmer, with the average minimum temperature in the last week of November and the first week of December remaining around 15° C. The average minimum temperature during the same period in 2011 was around 12°C,” said Sen.