A layer of dense fog engulfed the national capital and its nearby area - Noida and Gurugram - on Wednesday with minimum temperature hovering around nine degree Celsius.
The visibility has drop to below 100 metres severely affecting train and flight services here.
As per the Chief Public Relations Officer of the Northern Railway, 21 trains have been delayed, 13 cancelled and four rescheduled.
The Air Quality Index at Delhi's Terminal 3 airport was recorded to be 201 micrograms of PM2.5 and 220 micrograms of PM10.
The Meteorological Department has predicted a maximum temperature of 25 degree Celsius with lows of eight degrees.
Furthermore, shallow fog is expected to be seen in the national capital.