Heavy fog threw rail, road and air traffic out of gear in the city on Thursday with visibility dipping below 20 metres affecting schedules of around 80 flights.

Many trains ran behind schedule because of the poor visibility while road traffic moved at a snail’s pace.

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. The city is likely to witness dense fog during the Republic Day celebration on January 26.

The minimum temperature was recorded at 7.2 degrees Celsius on Thursday, against Wednesday’s 6.6 deg C while maximum temperature in the last 24 hours was recorded at 18.6 deg C -- two notches below normal.

An airport official said 27 domestic and international flights were diverted, 18 cancelled and around 20 rescheduled since last night because of the poor runway visibility.

On Wednesday, over 170 flights were either delayed, rescheduled or cancelled after dense fog enveloped the airport for over 11 hours.