Thick fog and heavy rains threaten to disrupt travel across Britain, forecasters warn

Areas of fog will develop on Tuesday night, initially across the western part of the warning area before spreading east overnight.

The warning covers huge swathes of the country, stretching from Southend-on-Sea in the south-east up to Thirsk in North Yorkshire.

It also spans east to west, with areas including Norfolk and Manchester falling within the same warning.

The Met Office has urged Britons to give themselves the best chance of avoiding delays if they intend to travel.

The UK’s national meteorological service advised people to check road conditions, allow extra journey time, or amend plans if necessary.

It also said travellers should ensure they know how to switch on their fog lights and check they are working before setting off.

Those planning to travel by bus, train or plane are advised to check for updates from their travel provider and follow any guidance issued.

A separate yellow warning will affect the south west, including parts of south Wales.

This warning differs in that it relates to heavy rain, which could lead to travel disruption and possible flooding.

Britons in affected areas have been told to expect heavy rain, especially over high ground, moving slowly east across the region on Wednesday.

It follows a period of very wet weather, with 10–20mm of rain likely to accumulate widely across the warning area.

The Met Office also warned that 40–60mm of rain is possible over high ground, including Dartmoor and the hills of south Wales.

Rain is expected to clear eastwards on Wednesday evening and into the early hours of Thursday.

Intense downpours carry a risk of flooding and power cuts.

The Met Office said that preparing in advance can help mitigate potential problems.

People are advised to gather torches and batteries, a mobile phone power pack, and other essential items.

The Met Office also recommends staying up to date with forecasts to prepare for rapidly changing weather conditions.