Rail and air traffic was affected as visibility dipped considerably due to dense fog that enveloped Delhi on Friday morning with the minimum temperature settling at 6.4 degrees Celsius.
Relative humidity was at 95 per cent, at 8.30 am.
Due to low temperature and high humidity, the air quality was in the "severe" category in the morning. According to Central Pollution Control Board (CPCB) data, Delhi's AQI at 8 am was at 430.
Visibility was zero at Palam and 300 metres at Safdarjung, at 5.30 am. Later, visibility improved at Palam (50 metres) but dipped by another 100 metres at Safdarjung around 8.30 am, a meteorological department official said.
Over 100 trains were running late by up to two hours while 10 flights were delayed due to dense fog, rail and Delhi airport officials said.
The weatherman has forecast a partly cloudy day with 'cold to severe cold conditions' in the city as the maximum temperature is expected to hover around 16 degrees Celsius.