Dense fog warning for parts of the South West
Visibility could fall to less than 50 metres in some places
A yellow weather warning for fog is in place across parts of the South West.
The Met Office has warned the dense fog could lead to travel delays.
The warning is in place until 10am, with visibility expected to fall to less than 50 metres in some places.
Parts of the West Country and central southern England are likely to be the slowest to clear.
"Fog will slowly lift and clear during Sunday morning; likely slowest across parts of the West Country and central southern England," the alert read.
The warning also covers London and south-east England, the east and west Midlands, Norfolk and Hertfordshire in the east of England, and parts of Yorkshire and Humber.
Parts of north-west England are included too, along with areas around Flintshire and Wrexham in Wales.
Travel advice
People are advised to allow extra time for travel, check road conditions ahead of time and make sure their fog lights are working.
The Met Office has warned that bus and train services, as well as flights and ferry travel, may also be affected.
"Bus and train services, as well as flights and ferry travel, may also be affected; check for updates from your travel company and follow their advice," the alert read.
Colder weather predicted later this month
The warning comes amid predictions that Britain could be hit by colder temperatures later this month.
A weakening polar vortex is threatening to bring Arctic air.
The polar vortex is a ring of powerful winds that helps keep freezing air near the North Pole.
If it weakens, it could allow colder Arctic air to sweep south towards Britain, increasing the risk of wintry weather.
Met Office forecaster Marco Petagna said: "At the moment, we've got a warming taking place in the stratosphere."
He added: "The polar vortex in the stratosphere is starting to weaken."
The Met Office will monitor the polar vortex over the next few weeks to see whether the disruption could bring colder conditions to Britain.