Roads in Birmingham and the Black Country have been partially blocked by flooding, causing traffic delays in the area.
Traffic service Inrix said the M5 northbound exit slip road was partially blocked with queuing traffic, due to flooding at the M6 junction eight.
This has caused congestion at the M5 Junction one, Inrix said.
The A453 Aldridge Road in Perry Barr, Birmingham, is also partially blocked around the junction with Old Oscott Lane due to flooding, according to West Midlands Roads.
The transport body also reported flooding under the railway bridge on Summer Road in Erdington and Brookvale Road in Witton.
The Met Office issued a yellow weather warning for thunderstorms and heavy rain on Wednesday, covering the whole of the West Midlands.
The warning is in place from 01:00 BST on Thursday and lasts for almost 24 hours.
The Met Office said there was a chance of heavy rain on Thursday morning, followed by thunderstorms and more showers in the afternoon.
It added that the afternoon storms could produce at least 50mm (2in) of rain in 1-2 hours, along with gusty winds, hail, and surface-water flooding.