Heavy fog which has caused travel chaos across the UK is expected to shroud parts of the country again on Thursday, forecasters said.
Dozens of flights were delayed or cancelled due to poor visibility at London City Airport on Wednesday morning, while a string of arrivals were diverted elsewhere.
A major crash on the A40, which killed one female driver and injured around a dozen others, happened after foggy conditions made it “really dangerous”, one witness said.
The Met Office said it was expecting to reissue a weather warning which had first been put out on Tuesday.
The original yellow fog warning said: “Patches of fog are expected to form overnight and whilst not all areas will see them, where fog patches do form visibility could be less than 100 metres.
“The fog patches are expected to slowly thin during Wednesday, although some patches may persist throughout the day.”
The forecast showed much of southern England blanketed by the fog.
At London City Airport, visibility on the airfield dipped as low as 50 meters, a spokesman said.
He added: “We have had several delays and cancellations and some arrivals diverted as well.
“We were able to to operate seven departures successfully, but the airlines have had to cancel around 22 departures. On arrivals, we have had around 14 cancelled.”
He added that they expected the fog to affect flights until around 2pm, with knock-on disruption continuing throughout the day.
Passengers were advised to check in advance with their airlines to see if they are likely to face delays, visit the airport’s website or talk to staff on the ground.
Meanwhile, a motorist on the A40 who witnessed the fatal pile-up said that the poor visibility meant it was difficult for cars to see each other before they were “on top of it”.
A Met Office spokeswoman said the low visibility and frosty conditions were caused by clear skies and dropping temperatures.
She added: “As we go through the next couple of days we will see less fog and frost as the weather gets cloudier.”
A severe weather alert has also been issued by the Met Office warning of plummeting temperatures across much of England.
A level three weather warning has been put in place until 11am on Friday after temperatures dipped below 2C in parts of northern, eastern and south-eastern England.
Public Health England (PHE) issued advice for the over 65s, those with long-term illness or who are not mobile.
Dr Thomas Waite, consultant in extreme events and health protection at PHE, said: “The effects of cold can be severe, in particular for those who are over 65, have a long-term illness, or are not mobile. Our advice to these groups is when indoors, have plenty of warm food and drinks and try to maintain indoor temperatures to at least 18C.
“If mobility isn’t an issue, keep active as best you can. If you need to go out wear lots of thin layers and shoes with a good, slip-resistant grip to prevent any accidental falls. It is particularly cold at night this week, so drawing the curtains at dusk will keep the heat in.”
He also stressed the importance of checking on potentially vulnerable family and friends during the cold period.