The Met Office has issued a yellow weather warning for wind and rain, starting at 10am and running until 7pm.
Forecasters are warning of a brief spell of heavy rain and strong, gusty winds which could lead to some transport disruption and flooding.
The forecast says: "A narrow band of rain, heavy at times and perhaps briefly intense, will move eastwards late on Thursday morning and into the afternoon. 10 to 15 mm is likely to fall in a 1 to 2 hour period, with around 20 mm in a few places.
"With saturated ground, this is likely to lead to a fair amount of surface water on roads and flooding in one or two places.
"Strong winds will be an additional hazard with gusts of 40-50 mph inland and perhaps briefly 60-70 mph."
The warning affects all of the West Midlands region - including the Black Country and parts of Staffordshire, although areas such as Walsall and Lichfield fall outside the official warning area - as well as the whole of Wales, the South West and most of the South East.
Drivers are being warned of extended journey times due to spray and flooding, as well as potential delays for high-sided vehicles on exposed routes and bridges.
It comes as flood alerts remain in place in the Black Country and Wyre Forest regions.
The Environment Agency (EA) has issued an alert for both River Stour and Smestow Brook in the Black Country and South Staffordshire, and the River Stour in Worcestershire, as a result of "persistent rainfall over the past few days and this morning".
The agency warns of flooding affecting low-lying land and roads adjacent to the nearby rivers with more rainfall expected today and tomorrow.
In its Worcestershire alert, the EA says it expects some flooding adjacent to the river between Caunsall and Stourport. Other locations that may be affected include Wolverley and Cookley, Blakedown and Kidderminster, although flooding of properties is not expected.
The agency added: "Please avoid using low lying footpaths and bridges near local watercourses and plan driving routes to avoid low lying roads near rivers, which may be flooded."