A thick blanket of fog and cold wave gripped New Delhi for the third consecutive day on Saturday severely affecting air, rail and road traffic.

As the mercury dipped to 7.5� Celsius, fog enveloped the city reducing visibility on the runway to less than 100 meters.

Not a single flight was able to take off or land at the Indira Gandhi [Images] International Airport between 0200 IST and 0900 IST, airport sources said.

Nearly 40 flights of Indian Airlines, Jet Airways [Get Quote], Air Deccan and Air Sahara were delayed.

Some international flights were also delayed.

Flights of several international airlines, including Lufthansa, could not land at Delhi airport and had to be diverted.

Trains too have been running behind schedule with the Ambala-bound Unchahar Express, scheduled to reach New Delhi at 0515 IST getting delayed due by over seven hours, Northern Railway officials said.

Foggy conditions are expected to continue till around noon and the temperature is likely to stay at about 16� C, a good seven degrees below normal.

The minimum temperature forecast for Sunday is in the range of 6� C, while maximum temperature on Friday was 15.3� C, eight degrees below normal.