NEW DELHI: A dense layer of fog is expected to engulf Delhi on Tuesday with the meteorological department issuing a yellow alert for the day.
The maximum temperature on Monday was recorded at 17.6 degrees Celsius, three notches below the season's average.
The minimum temperature was recorded at 6.1 degrees Celsius as against 4.8 degrees Celsius the previous day, the weather office said.
Safdarjung, Delhi's main weather station, recorded a visibility of 500 metres at 5.30 am, while the visibility at the Indira Gandhi International Airport was 1,000 metres at 6.30 am.
The India Meteorological Department (IMD) has forecast mainly clear sky and moderate to dense fog in the morning for Tuesday with the maximum and minimum temperatures likely to settle around 18 and 7 degrees Celsius, respectively.
According to the Indian Railways data, 23 Delhi-bound trains were running late due to dense fog that enveloped parts of northern India.
Humidity levels oscillated between 55 per cent and 95 per cent on Monday.
The 24-hour average Air Quality Index (AQI) recorded at 4 pm on Monday was 333, which falls in the "very poor" category.
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".