A yellow weather warning has been issued for Greater Manchester as heavy rain looks set to batter the region.
The Met Office has warned homes and businesses are at risk of flooding and transport could be disrupted in places.
Forecasters have put a warning in place throughout Wednesday and during Thursday morning.
A spokesman said: "Around 20 to 40 mm of rain could widely fall, with 50 to 80 mm possible over high ground and as much as 100 mm in a few locations.
"There is a small chance that homes and businesses could be flooded, causing damage to some buildings."
Drivers have also been warned conditions could become treacherous on the roads.
They continued: "Where flooding occurs, there is a slight chance of delays or cancellations to train and bus services.
"Spray and flooding could lead to difficult driving conditions and some road closures.
"There is a small chance that some communities become cut off by flooded roads."
The weather is likely to remain unsettled for the rest of the week.
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