UK fog flight delays hit London's airports on Friday morning. The Met Office issued a fog warning covering London, the South East and the East of England until 10 a.m. UK time, and while the fog has since lifted, flights at Gatwick, Heathrow and Stansted are still running well behind schedule. Most arrivals at Gatwick and Heathrow have landed late, many by more than an hour, and London City has canceled several flights. Forecasters had flagged Friday as the riskiest morning of the week, and more fog was expected Saturday, so if you're flying this weekend, the disruption may not be over yet.
Latest Updates
Friday, 9:35 a.m. ET: The fog arrived. The Met Office's warning for London, the South East and the East of England ran until 10 a.m. UK time, and London's airports are still working through the delays it left behind. At Gatwick, 26 of the last 30 arriving flights landed more than 15 minutes late, 20 of them more than an hour late, and departures are averaging close to an hour behind schedule. At Heathrow, 24 of the last 30 arrivals were late and departures are averaging about 45 minutes late and rising, according to our own analysis of flight-tracking data. London City has canceled at least five flights, and Stansted arrivals are running around 35 minutes late. Expect knock-on delays into the afternoon as planes and crews catch up.
Wednesday, 8 a.m. ET: Thursday morning now looks like the most likely time for fog. Forecasters say dense patches could form overnight across southern and central England and be slow to clear, which is when London's airports are most at risk of delays. No official fog warning has been issued yet.
Tuesday, 10 p.m. ET: No fog warnings yet. The Met Office expects the first fog to form Wednesday night UK time. We'll update this section as warnings, cancellations or airline announcements come in.
Why the Delays Last After the Fog Lifts
By the time the sun burned through, the damage was done. During the worst of the fog, London's airports could only handle a fraction of their usual flights, so planes headed there were held at their departure airports or slowed down en route. Once visibility improves, all those late flights try to arrive at roughly the same time, and the planes and crews that should have left London on time are now hours behind. One bad morning can ripple through the rest of the day's schedule, which is why Gatwick departures are still running close to an hour late well after the warning expired.
Heathrow makes it worse. It runs close to full all day with only two runways, so there's almost no spare room to absorb a slow morning. Gatwick, the world's busiest single-runway airport, has even less. Any flight that misses its slot gets pushed further down the line, and the afternoon inherits the morning's problems.
Why Fog Slows Flights
Planes can land in thick fog. The problem is how many can land. When visibility drops, air traffic controllers switch to low-visibility rules that space planes further apart, both in the air and on the ground, so fewer flights can use the runway each hour. At airports that are already packed, airlines often have to cancel flights to make the schedule fit.
It's happened before. Over two foggy days in late December 2024, more than 200 flights were canceled across UK airports. Heathrow and London City each lost more than 40, mostly British Airways flights at Heathrow, and Gatwick had 48 canceled in a single day. Short flights to and from Europe are usually the first to go, since those passengers have other options like trains or a later flight, while long-haul flights to the US and Asia are protected as much as possible. US airports aren't immune either, as fog in Denver showed earlier this week.
If You're Flying Today or This Weekend
Check your flight before you leave for the airport, and keep checking. If your plane is coming from somewhere else, it may still be running hours behind even though London's skies are clear. If you're connecting at Heathrow, look at later options now in case a late arrival costs you your onward flight, and if you're picking someone up, don't trust the original arrival time.
For Saturday, check the night before and again in the morning, especially for early departures, when fog is usually thickest. Airlines often cancel short-haul flights the evening before once the forecast firms up, so you may get an email or app alert before you leave home. If your flight is canceled and it's covered by UK or EU rules, which includes any flight leaving the UK, your airline has to offer a refund or a new flight, and while you wait it should cover meals and a hotel if you're stuck overnight. Because fog counts as weather, you won't get extra cash compensation on top of that.
Heading on to Italy? Friday's strike there has so far barely touched flights or trains, so London's fog is the bigger worry today.
