Delhi witnessed a cold Christmas, with the minimum temperature settling at 6 degrees Celsius, the weather department said on Wednesday.
The city witnessed moderate to dense fog in the morning. The maximum temperature settled at 12.7 degrees Celsius, nine notches below normal, officials said.
They said a cold wave is likely to hit Delhi as the mercury is expected to drop to 4 degrees Celsius on the weekend.
Since December 16, the national capital has registered nine cold days, equal to that recorded in 2003.
The city recorded the maximum of 17 cold days in December 1997.
According to Kuldeep Srivastava, head of the India Meteorological Department's regional forecasting centre, a "cold day" is when the maximum temperature is at least 4.5 notches below the normal.
A "severe cold day" is when the maximum temperature is at least 6.5 degrees Celsius below the normal, he said.
Meanwhile, moderate wind speed led to a slight improvement in the air quality on Wednesday. The overall air quality index was recorded at 350 at 4 pm, down from 383 on Tuesday.
The government's air quality monitoring and forecasting service SAFAR said an extended period of calm surface winds with high humidity is predicted December 27 onwards, which will have an adverse affect on the air quality.