Traffic crawled on Delhi roads following the dense fog. Over 200 flights were also affected.
Delhi is experiencing the worst fog since 2010, severely disrupting air, road and rail traffic in the national capital.
With visibility below the mandatory 50 metres, all flight operations at the Indira Gandhi International Airport have been suspended, affecting hundreds of flights. Officials say there is little possibility of visibility getting better before 9 am on Monday morning.
With flights not taking off, there were reports of chaos at Terminal 3 of the airport with passengers reportedly complaining that they were not being allowed to exit the airport because of security reasons.
With maximum visibility staying at less than 600 metres through Sunday, around 206 flights got delayed and with no relief expected till tomorrow, those planning to travel may have to face difficulties.
Dense fog also slowed the Sunday evening traffic on the roads with visibility in some areas reported at less than 10 metres.
The blanket of thick fog over the national capital also hit train services with dozens of trains running behind schedule or cancelled.
Delhi woke up to a foggy morning on Sunday as the minimum temperature settled down at 7.8 degree Celsius, one notch below normal. Met officials said due to low temperature, absence of heavy wind and moisture incursion from Madhya Pradesh, weather conditions were favourable for intensification of fog in Delhi and adjoining parts of the northwest plains.
Apart from the national capital, thick fog has also been reported from various cities in Haryana, Uttar Pradesh and Madhya Pradesh. Cold wave conditions continue across most parts of north India with temperatures at most places remaining below normal.