The Met Office has issued a yellow weather warning for Herefordshire, Monmouthshire, Shropshire, Worcestershire and Gloucestershire.
Forecaster said 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.
The warning will be in force from 10am until 7pm on Thursday.