The snowfall was forecast to lessen later in the day but unusually cold temperatures, even for the time of year, well below freezing were expected throughout the week Flag carrier Turkish Airlines (THY) cancelled over 600 flights - including all domestic routes until the evening - as efforts continued to clear snow from its hub of Ataturk International Airport.
THY chief executive Bilal Eksi said on his Twitter account over 10,000 travellers unable to reach Istanbul had been accommodated in hotels while well over 5,000 who could not leave were accommodated in the city.
After angry complaints from some stranded travellers on social media, he added: "We are working to ensure our passengers do not suffer in these difficult conditions." He said the problems were due to a lack of take-off and landing slots at Ataturk in the snow conditions, with only 172 take-offs and 209 landings scheduled on Sunday.
On a normal busy day, the airport can accommodate over 1,500 landings and take-offs.
The Istanbul municipality meanwhile sent over 1,300 vehicles and 7,000 personnel into the streets to clear the snow.
Copyright Agence France-Presse, 2017