"Some flights were delayed and some diverted because visibility at the airport runway fell below 50 metres," an airport official said.
According to an update from airport officials at 12 noon, nine flights with destinations to Jaipur, Ahmedabad and Lucknow were diverted.
Even a few trains coming to Delhi were running behind schedule, slowed down by dense fog.
"No trains have been cancelled so far, but a few coming to Delhi and going further from here are now running behind schedule," a spokesperson for Northern Railway said.
The India Meteorological Department (IMD) has, however, forecast a clear day ahead for the national capital.
The minimum temperature settled at 8.8 degrees Celsius in the city, average for this time of year.
"The day's maximum temperature is likely to hover around 24 degrees Celsius," the IMD official said.
Sunday's maximum temperature was a notch above the season's average at 24 degrees Celsius, while the minimum temperature settled a notch above the season's average at 9.4 degrees Celsius.
--IANS (Posted on 16-12-2013)