Dozens of flights have been cancelled at Heathrow airport due to thick fog.
A spokeswoman for Britain's busiest airport said the weather had forced the cancellation of about 50 flights and advised passengers caught up in the disruption to contact their airlines.
"The fog has been quite bad today," she said.
"We've had to cancel flights to keep up with the schedule. Passengers are advised to check with their airlines."
The fog is due to clear by 3pm and no further cancellations or delays are expected today, the Heathrow spokeswoman said.
Passenger Ed Drewett wrote on Twitter: "Stuck on the ground at Dublin due to fog at Heathrow. Gonna miss my flight to LA. Ooh I do love a drama."
Another Twitter user said: "So fog at Heathrow means cancelled flight and 1 extra night in sunny Palma. Thank you @britishairways and @Iberia for looking after us."