Some passengers at Manchester Airport are facing delays of up to two hours.
“Like most airports across the country, we have experienced some delays as a result of fog,” a spokesperson said.
Passengers have been told to arrive at the airport “as normal”, as most delays “have been short and have not caused disruption to our schedule,” they added.
A London Gatwick spokesperson said temporary air traffic restrictions had been put in place due to fog causing poor visibility.
“Some flights may be delayed throughout the day,” they added.
“London Gatwick apologises for any inconvenience. Passengers should contact their airline for further information.”
Meanwhile, National Highways, which runs the UK’s motorways and busiest A-roads, said the misty weather was not having a significant impact on its network.
It reminded motorists to use dipped headlights, wipers and demisters while driving in foggy conditions.