Disruption to travelpublished at 11:38 BST
11:38 BST
Bea Swallow
West of England
Transport operators have also warned of potential disruption, with high temperatures capable of affecting road surfaces and rail infrastructure.
Great Western Railway announced it was running an amended service following the weather warning and urged passengers to check journey times before they travel.
Image source, PA Media
National Rail says it will be closely monitoring sections of railway track to detect whether the steel is expanding or curving, and will introduce speed restrictions to prevent further buckling.
National Highways South West warned tarmac can also soften in extreme temperatures.
“In the most severe cases, we consider closing lanes for safety reasons,” it said.
“We monitor the network very closely during these times, so that we can carry out necessary repairs as quickly as possible.”