The Met Office says flash-floods could occur across Preston and Lancashire today and Thursday.
Showers, often heavy with isolated thunderstorms, may become more frequent across northwest England during Wednesday evening and into Thursday.
The region is currently facing a yellow weather warning, meaning that spray and road flooding will likely make journey times longer. The flooding of a few homes and businesses is also likely, and bus and train services may be affected.
Read more: Hour-by-hour weather forecast as Preston and Lancashire thunderstorm warning remains
Some places could see 15-20 mm of rain within an hour and as much as 40-60 mm over a six-hour period.
The news follows yesterday’s announcement that Preston and Lancashire will experience thunderstorms today, with buildings and homes at risk from lightning strikes.
Read more: See the latest Preston news and headlines