The minimum temperature in Delhi dropped 5.3 degrees Celsius on Friday due to icy winds coming from the hill states.
The city recorded a high of 17.5 degrees Celsius, two notches below the normal.
Some parts of the city witnessed dense fog in the morning. The Palam weather station recorded dense fog that brought down visibility to 150 metres at 5.30 am, a MeT department official said.
Twenty-three north-bound trains were delayed by up to 3.5 hours, said a Northern Railway spokesperson.
The temperature is expected to drop further in the next two to three days.
Mahesh Palawat, vice president (meteorology) at private forecaster Skymet Weather, said the mercury will drop further over the weekend due to icy winds coming from the north.
Another spell of rains is expected in Delhi-NCR around January 13-14 due to a fresh western disturbance, he said.