The weather office reported shallow to moderate levels of fog in many parts of the city. Safdarjung observatory recorded visibility at 200 metres.
The formation of smog -- the combination of smoke and fog -- can be attributed to last night's incessant fireworks during the festivities.
The minimum temperature was recorded at 15.5 degrees Celsius, normal for this time of the year, while the maximum is likely to be around 31 degrees Celsius.
The sky will be clear in the later part of the day, an official said.
Yesterday, the maximum and minimum temperatures were 31.7 and 15 degrees Celsius respectively.