The city was hit by the season's worst fog on Sunday.
The visibility dropped to 300 metres in Delhi Monday morning.
"My flight has been diverted to Ahmedabad, thanks to Delhi fog," Anuja Mohan, who was on her way to Delhi from Dubai, told IANS.
People waiting at the city's two airports for their flights complained that the authorities were not providing information about the delays and cancellations.
"Original departure time was 6.40 a.m. It was rescheduled to 8.45 a.m. due to fog. Even an hour later, nobody is still bothered to explain what the real problem is," said Dinkar Krishnan, who was to travel to Chennai.
According to the Northern Railway, 44 trains en-route to Delhi were running behind schedule and five were rescheduled.
Commuters travelling from Delhi to the satellite towns of Noida in Uttar Pradesh and Gurgaon in Haryana faced a harrowing time.
The minimum temperature Monday settled a notch below the season's average at 6.6 degrees Celsius. However, the Met Office said the sky will remain mostly clear later in the day.
The maximum temperature is likely to hover around 19 degrees Celsius.
Humidity at 8.30 a.m. was 100 percent.
Sunday's maximum temperature settled one notch below the season's average at 19.3 degrees Celsius, while the minimum temperature was a notch above the season's average at 7.8 degrees Celsius.