Fog affected passenger flights again today, with a number of services in and out of UK airports having to be cancelled.
But after having to axe some early-morning flights, Heathrow reported that conditions had improved, with the fog lifting.
Forty arriving flights and 24 departing ones were cancelled today at Heathrow.
Destinations affected included Manchester, Glasgow, Amsterdam, Brussels, Stockholm, Cologne and Nice.
Ten departing flights at London City Airport were also axed, with services to Dublin, Rotterdam and Paris among those hit.
One flight scheduled to leave Leeds Bradford Airport earlier today was cancelled. The 6.20am KLM service had been due to fly to Amsterdam, which has also been affected by fog.
The early-morning problems followed severe disruption to flights due to fog yesterday, with Heathrow having to cancel 81 departures and 65 arrivals.
Today a Heathrow spokeswoman said: "Heathrow experienced heavy fog on Sunday and overnight. Today we are aware of 40 inbound and 24 outbound flights that have been cancelled. The fog has started to clear and there are now no restrictions on flying.
"There are currently no delays to flights but we advise passengers to check with their airlines before travelling."