Fog started to descend at the airport around midnight and general visibility plunged below 50 metres at 3am.
Visibility started improving only after 8am and low visibility procedures were lifted at 11.35am.
A total of 95 flights were operated using different categories of the Instrument Landing System, which helps pilots land in poor visibility conditions.
The third runway of the airport, which witnesses more dense fog than runway 28, could not be made operational between 3am and 7am.
Even runway 28, the main workhorse of IGIA, somehow managed to meet the minimum criteria of visibility to operate.
The Met department believes the situation will improve in the next two days.
"We have been witnessing dense fog at night since January 2 but it is expected to weaken in the next two days," said a Met official.