A MeT Department official said that visibility at Palam and Safdarjung oscillated between 700 to 800 metres.
70 trains are running late by several hours due to fog, a Railway spokesperson said.
Humidity in the national capital was recorded at 95 percent.
The weatherman has predicted light trains for today evening or late night.
Yesterday, the minimum temperature was recorded at 10.4 degrees Celsius, three notches above normal, while the maximum settled at 25.4 degrees Celsius, six notches above the season's average.