The Met Office has issued a yellow weather alert warning for rain and possible flooding for Greater Manchester.
It is in place from 12am on Wednesday until 12pm on Thursday.
A statement on the Met Office website read: "Heavy rain is expected to affect the region throughout Wednesday, only slowly easing during Thursday morning.
"Around 20 to 40mm of rain could widely fall, with 50 to 80mm possible over high ground and as much as 100mm in a few locations."
Meteorologists said there is a small chance homes and businesses could be flooded.
Bus and train services could be delayed by flooding, while there could also be some difficult driving conditions and road closures.
According to weather experts, the south of the region is more likely to be affected
Cheshire, Warrington and Halton have also been included in the warning area.
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Before the rainy spell reaches the region it will be cool, cloudy with some showers.
On Monday, there will be highs of around 17C, with temperatures dipping to 4C overnight.
Tomorrow (Tuesday), it will be cloudy throughout the day with some heavy showers.
It will be windy, with temperatures reaching highs of 13C.
The unsettled weather is likely into on Wednesday and Thursday.
Showers will not be as heavy, but will persist into Friday.
It will also feel rather chilly and temperatures will be below average.
Winds will be be strong for this time of year.
By next week, temperatures are expected to climb.
A statement on the Met Office website said: "Moving into the weekend this unsettled theme is likely to continue with further spells of rain and showers.
"Temperatures should be below average, especially in the wetter areas.
"Through the following week there will probably be more in the way of drier spells with west and northwest the most favoured locations for this, but still with outbreaks of rain or heavy showers at times."
