A red warning for extreme heat has been issued for parts of Shropshire and Worcestershire on Monday and Tuesday, when temperatures could reach 40C for the first time.
The Met Office is warning of "an exceptional hot spell [...] leading to widespread impacts on people and infrastructure".
"Population-wide adverse health effects" are expected, "not limited to those most vulnerable to extreme heat".
Elsewhere, an existing amber warning for Herefordshire and Monmouthshire will remain in place from Monday.
The Met Office has said the warnings mean "adverse health effects" may be experienced and will not be limited to "those most vulnerable to extreme heat"
They added the weather could also lead to "serious illness or danger to life".