As the city celebrated Christmas on Tuesday, it was the coldest day of the season with the mercury dropping to 19.5 degrees Celsius, two notches below the season's average.
The day's minimum temperature was recorded at 5 degrees Celsius, three notches below the normal, a MeT department official said, adding that it was the coldest day of the month.
The minimum temperature is likely to dip to three degrees Celsius after December 28, the official said.
A heavy blanket of fog engulfed the national capital in the morning on Tuesday with visibility dropping to 50 metres.
Flight operations were partially suspended at the Delhi airport due to low visibility as departures were put on hold and more than 80 flights were delayed, an official said.
Humidity oscillated between 100 and 52 per cent.
The weatherman has predicted moderate fog on Wednesday morning with the maximum and minimum temperatures likely to settle around 20 and 4 degrees Celsius respectively.
On Monday, the maximum and minimum temperatures were recorded at 22 and 3.7 degrees Celsius, respectively.