A thick blanket of fog engulfed the national capital on Monday morning affecting train and flight operations as visibility dropped drastically, with some observatories recording it at zero metres.
The minimum temperature settled at 2.6 degrees Celsius, four notches below the season's average, and humidity was 100 per cent.
Delhi's air quality index was in the severe category at 450 at 8.38 am.
The visibility recorded by the Safdarjung and Palam observatories stood at zero metres at 8.30 am. It was recorded at 100 metres at Safdarjung and zero at Palam at 5.30 am.
Three flights were diverted from the Delhi airport due to heavy fog, but according to an update at 7 am, an airport official said, "no flights have been cancelled yet".
Thirty trains were delayed and the delay ranged from two to seven and a half hours, according to a Railways official.
More From This Section
The Delhi-Bhubaneshwar Rajdhani was delayed by seven and a half hours.
The weatherman has forecast mainly clear skies for the day with the maximum temperature likely to hover around 16 degrees Celsius. Foggy conditions will continue to prevail on Tuesday with the minimum temperature likely to settle around three degrees Celsius.