The minimum temperature settled, two notches below the season's average at 6 degrees Celsius.
Visibility was 300 metres at 5.30 AM and 8.30 AM. The Met Office has forecast a clear day ahead.
Dense fog has severely affected operations of all north bound trains, according to a Northern Railways official.
There are as many as 90 trains that are running late including Rajdhani coming from Ranchi, Kolkata, Bubhaneshwar and Guwahati. Northern Railways has rescheduled departure of 13 trains and cancelled five trains due to adverse weather conditions, the official said.