Britons have been warned of potential disruption to flights and delays on roads as freezing fog sets in across much of south-east England.
Forecasters have issued a yellow warning as the severe weather could prove dangerous as the mist descends and severely reduces visibility.
Freezing fog patches developed overnight and are expected to cause delays for commuters in London and the rest of the south-east on Tuesday morning.
While the dense fog is set to clear from most places as the day progresses, some regions could experience the grey and misty conditions into the evening.
The Met Office warning was put in place at 12.15am and is expected to remain in effect until 11am.
In its alert, the weather service warned that commuters could expect slower journey times with delays to bus and train services.
Don't 4get to allow extra time if you're about and about travelling tomorrow morning, as it will #frosty and #foggy in places. 4tunately though Tuesday looks mostly dry with some #sunshine developing. Here's the 4cast: pic.twitter.com/R8hwBDbSuz
— Met Office (@metoffice)
There is also a chance of disruption to flight travel amid the severe conditions, as airports could put cold weather plans in place.
Temperatures were expected to plunge as low as -5C in some parts of the country, with Devon and Cornwall residents shivering in -4C overnight.
Met Office meteorologist Alex Burkhill said Britons can expect the freezing overnight temperatures to continue throughout most of the week.
“It is not until Thursday into Friday that it will be much milder so there are lots of cold, frosty nights to come,” he added.
The weather warning in the south-east include greater London, East Sussex, Surrey, Brighton and Hove, Buckinghamshire, Reading and Portsmouth.
It also covers Cambridgeshire, Essex, Suffolk and Thurrock.