As Istanbul braces for a second wave of heavy snowfall, a total of 463 flights have been canceled at Istanbul's Atatürk and Sabiha Gökçen airports. The highest number of flight cancellations have been issued by Turkish Airlines. The airline said in a statement Wednesday that 327 of its flights on Jan. 26-27 were canceled due to the expected heavy snowfall across Istanbul.

Meanwhile, Turkey's biggest private airliner, Pegasus Airlines announced that 110 flights to and from Sabiha Gökçen Airport have been canceled preemptively due to bad weather conditions, also warning passengers of unexpected delays.

Turkish airliner AtlasGlobal also canceled 20 flights, whereas OnurAir said that six of its flights were canceled so far.

The flight capacity of two airports in Istanbul has been reduced by 20 percent until tonight and further cancellations might be announced in the upcoming days.

All passengers are advised to check with their airlines for adjusted schedules or cancellations.

According to forecasts, temperatures in Istanbul will drop by 7 degrees Celsius coupled with 60 km/h northeasterly winds. Heavy snowfall is expected to start around yesterday morning, lasting for about four days in Istanbul and the surrounding area.