Heavy rain has been forecast to hit Weston-super-Mare and North Somerset tomorrow (Tuesday).
The Met Office said the warning will be in place from 4am-3pm on Wednesday.
Torrential downpours could lead to difficult driving conditions and some road closures.
A Met Office spokesman said: "Rain and heavy showers bring a risk of flooding and travel disruption.
"Expect spray and flooding on roads, which will probably make journey times longer.
"Bus and train services will probably be affected and the flooding of a few homes and businesses is likely."
Road users are advised to check road conditions before they travel, to take extra care when travelling and allow plenty of extra time to complete their journey.
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