The lowest minimum temperature recorded was 2.6 degrees on December 29 which was the fourth lowest in the last 50 years after 2013, 1996 and 1973.
The lowest minimum temperature ever recorded in Delhi is 0.0 degrees Celsius on December 27, 1930.
There were 14 nights with minimum temperature below 6 degrees and eight nights when the minimum temperature was less than or equal to 4 degrees, thus, meeting the threshold of cold wave and ground frost conditions, the IMD said.
The average maximum temperature during December was 23 degrees which was normal for the month.
The fog coverage data (hours) at IGIA, Palam showed that it was the clearest month in the last 22 years in terms of visibility.
Fog hours (shallow to very dense) during the month were only 145 against normal of 300 hours. Dense fog conditions were also subdued with just two nights of 9 hours against normal of 9 nights and of 45 hours, the IMD said.