More than 40 domestic and international flights have been delayed, while nine arriving and departing flights were cancelled.
The visibility at the runway dropped to 50 metres as a result no flights could take off since 6:AM. The minimum visibility is 125 metres and 150 metres for various categories of aircraft.
The visibility started to decrease in the wee hours as a result one Jet Airways flight from Doha was diverted to Jaipur.
As the visibility hovered between 75 metres and 50 metres, some of the flights landed using CAT III B instrument landing system, which allows a compliant aircraft to land when the runway visibility is 50 metres.
The visibility is likely to improve as the day progresses, according to Met department.