Dense fog has caused travel chaos in India's capital Delhi, with dozens of flights and trains affected.
Report say 50 flights and nearly two dozen trains have been delayed.
According to the flight tracking app flightradar24, hundreds of departing flights were delayed by 25 minutes on an average and flight arrivals were delayed by eight minutes.
But passengers have been complaining of being stranded for hours at the airport.
Delhi airport authorities had issued a flight advisory on Monday, asking passengers to contact their airlines to check for updated flight information.
"While landings and take-offs continue at Delhi airport, flights that are not CAT III compliant may get affected," the advisory read. CAT III runways make it possible for planes to land during poor visibility.
In December, fog and poor visibility in the city had resulted in more than 100 flights being delayed. The airport witnessed massive travel chaos in January too, with dozens of people taking to social media to complain about delays and cancellations.
On Wednesday morning, videos and photos from different parts of Delhi and suburbs showed a blanket of fog covering many roads and obscuring buildings. The Indian Meteorological Department (IMD) said the visibility had dropped to zero in several localities.
The IMD has predicted light rains or thundershowers, accompanied by gusty winds, on Wednesday. The department has also predicted moderate fog for the next few days.
Dense fog is common in Delhi and the rest of north India during winters, but the cold in Delhi this season has tumbled many records.
An IMD report says Delhi has experienced the coldest January in 13 years with maximum temperature recorded at 17.7C. The second coldest January was nine years ago - in 2015 - when a maximum temperature of 17.9C was recorded in the city. Nights too have been coldest this year after 2013, the report adds.
