A new warning for dense fog has been issued by the Met Office – with people being told to expect "difficult travelling conditions".
A yellow weather warning for fog stretching from Wales across central and into eastern England, then parts of the South East, will apply from 6pm on Monday until 10am on Tuesday.
The Met Office warned visibility will be reduced to less than 100 metres (328ft).
Forecasters said there could be cancellations or delays on travel networks, including flights, and encouraged people to leave extra journey time or to consider amending their plans.
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The weather agency told motorists to check road conditions, adding: "Make sure you know how to switch on your fog lights, and check they are working before setting off on your journey.
"Bus and train services, as well as flights and ferry travel may also be affected."
Motorists are also being advised to leave a large distance from the vehicle in front, while full beam should be avoided because fog reflects the light back.
It comes after foggy conditions produced a difficult morning commute for areas of the UK on Monday.
A yellow warning stretched from York to Bath and covered most of the South East and eastern England, as well as parts of Wales and Northern Ireland.
On Saturday, a stretch of the M20 in Kent was shut, and two people were seriously injured, after more than 30 vehicles were involved in a crash in thick fog.
Forecasters said the fog is likely to be less of an issue later in the week, but conditions are expected to turn "much colder".
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Sky News meteorologist Dr Christopher England said: "We've a change on the way, firstly with cloud, wind and rain moving into the South tonight and tomorrow, clearing the fog there, although it will form widely over central England and eastern Wales tonight, clearing only slowly tomorrow.
"The cloud will spread further north tomorrow night, while colder, drier air will extend south across northern parts, meaning any fog will be limited in extent and largely confined to Northern Ireland, northern England and southern Scotland.
"It will turn much colder and essentially fog-free thereafter, with long sunny spells for many, but there will be showers in the North, wintry on the hills, and sharp overnight frosts in the North and west."
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