Delhi witnessed moderate fog on Saturday morning while the minimum temperature settled at 8.9 degrees Celsius, two notches above the season's average, according to the India Meteorological Department (IMD).
The visibility at Safdarjung, Delhi's main weather station, and Palam was 500 metres at 5:30 am, the IMD said.
The relative humidity stood at 100 per cent at 8:30 am.
Train services were impacted due to fog with 14 Delhi-bound trains delayed, according to officials.
Delhi's Air Quality Index (AQI) was recorded at 315, in the 'very poor' category, at 9 am, according to Central Pollution Control Board data.
An AQI between zero and 50 is considered 'good', 51 and 100 'satisfactory', 101 and 200 'moderate', 201 and 300 'poor', 301 and 400 'very poor', and 401 and 500 'severe'.