Persistent and at times heavy rain looks set to cause flooding in the county.
There is a yellow weather warning in place for Sunday, September 23, between 6am and 11.59pm.
The Met Office has said people should expect "flooding of a few homes and businesses."
There could also be difficult driving conditions and longer journey times.
Strong winds are also expected.
The Met Office has also said they are unaware where the rain will fall the most.
A spokesman said: "Whilst there remains some uncertainty in the precise track and intensity of the system, and thus the location of the heaviest, most persistent rainfall, many places could see 20-30mm, with up to 50mm possible in some isolated spots.
"With strong winds also forecast in places, and recent heavy rain, drains and culverts blocked by debris could mean impacts in places which would not normally be affected by these rainfall amounts."