"The fog started accumulating at around 8.30 pm last night. The visibility dropped to 100 metres at 7.30 am," a Met Department official said.
Many trains were running behind schedule because of poor visibility while road traffic moved slowly. Motorists had to manoeuvre through a thick layer of fog in the morning hours.
Fog started to descend at the IGI airport around 1.30 am, reducing general visibility to zero. The runway visibility was above 600 metres but dropped to 75 metres in the wee hours.
Schedules of over 70 domestic and international flights were disrupted. Yesterday, Delhi airport witnessed chaos as over 200 flights were delayed, 25 cancelled and 28 diverted. The dense fog will continue for the next five to six days due to "unstable weather conditions" and high humidity level, a Met official said.
He said western disturbance is likely to pass through the city on January 23 which may result in rain and further deterioration in the weather condition. Delhi is likely to witness dense fog during the Republic Day celebrations.
The minimum temperature was recorded at 7.4 degree Celsius today, against yesterday's 7.2 degree C while the maximum was at 20 degree C, compared to 18.6 degree C yesterday. Both the temperatures were a notch below normal.
The weatherman predicted more fog for tomorrow. The maximum and minimum will hover around 21 degree C and 8 degree C, respectively.