Twenty-seven trains were delayed and flight operations delayed after thick fog engulfed the national capital on Monday morning.
The minimum temperature settled at 8 degrees Celsius, a notch below the season's average.
"Twenty-seven trains were delayed with an average delay of around three to four hours," the railways said.
The trains delayed included the Malda-Delhi Farakka Express and Allahabad-New Delhi Duronto.
The visibility at Safdarjung was recorded at 200 metres at 5.30 am that reduced to 100 metres at 8.30 am, a meteorological (Met) department official said.
At Palam the visibility was 50 metres at 5.30 am and 8.30 am which led to the disruption of flight operations at the Indira Gandhi International airport.
"Due to fog, some flights have been put on hold at the departure points. This has led to a delay," a source at Delhi airport said.
However, he added that "largely, there have been no diversions or cancellations of flights" as yet.
The minimum runway visibility required for take off at Delhi is 125 metres.
The Met office has forecast clear skies for the day ahead with the maximum temperature likely to settle at 21 degrees.
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