London's Heathrow Airport said airlines had cancelled 80 out of 1,350 flights, with disruption expected from 1500 GMT.
Four flights at Gatwick Airport have also been cancelled.
Heathrow Airport said without the cancellations it could not reschedule any flights delayed by the weather as 6 per cent of its usual daily flights were cancelled.
The Met Office has issued yellow warnings for snow for much of the UK from today.
The "be aware" warnings are in place for many areas of the country until Saturday.
Frequent snow showers and strong winds are expected widely across Scotland, Northern Ireland, Wales and the north of England on Thursday and in the south, rain is forecast to turn to snow.
Severe wintry weather has already hit Scotland, Wales, Cumbria and Bradford and is expected to move across the UK during Thursday and Friday, with temperatures plummeting to -10 degrees Celsius in areas.
Paul Gundersen, chief meteorologist at the Met Office, said "Most northern areas are very likely to see snow showers at times over the next few days, but the situation over the southern half of England is more complicated".
"Southern counties of England and Wales can expect a cold and wet day with some heavy rain on Thursday, but there's an increasing chance this will turn to sleet or snow, especially over hills, during the afternoon and evening."
"There is a chance of snow settling bringing disruption to transport during the evening rush hour and possibly interruptions to power supplies, this more likely across East Anglia and southeast England. As skies clear on Thursday night it is likely to become icy in many areas".
On Friday the cold weather is expected to continue with snow showers will becoming more isolated.