Dense fog returned to the national capital Thursday, affecting flight and train operations. The Met Office has forecast a clear sky Friday.
Visibility dropped to below 50 metres early Thursday morning due to dense fog.
Airport authorities said seven flights were delayed due to the poor visibility.
"Due to the dense fog in Delhi, all flights from Mumbai have been delayed by at least 40 minutes," Rinan Shah, who flew to Delhi from Mumbai, told IANS.
Northern Railway said running of 25 trains was affected.
Commuters travelling from Delhi to satellite towns Noida in Uttar Pradesh and Gurgaon and Faridabad in Haryana also faced problems.
"It took me more than the normal time as visibility was zero on NH-8," said Abhishek Mahapatra, who works in an IT firm in Gurgaon.
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Thursday's minimum temperature settled a notch above the season's average at 10.2 degrees Celsius. The maximum temperature was recorded at 20.5 degrees Celsius, a notch below the season's average.
Humidity at 8.30 a.m. was 100 percent.
The Met Office has forecast that moderate or dense fog is likely to engulf the city Friday morning.
"The sky will become clear in the day. The maximum and minimum temperature would be around 20 and 10 degrees Celsius respectively," said an an official of the India Meteorological Department.
Wednesday's minimum temperature settled at 10 degrees Celsius, a notch above the season's average, while the maximum was 22 degrees Celsius.