Heavy rain could lead to flooding and transport disruption for parts of Northern Ireland from Wednesday night.
The Met Office has issued a warning for rain mainly for counties Antrim and Down from 20:00 BST on Wednesday until noon on Thursday.
The downpours are expected to affect several regions, with the most significant rainfall predicted towards the east coast.
The rain will become persistent and heavy overnight with between 30mm to 50mm of rain likely quite widely.
Higher ground such as the Mourne Mountains could see up to 80mm of rain accumulating.
Despite the recent dry conditions, the heavy rainfall could lead to flooding in vulnerable areas and cause disruption.
The rain is expected to ease by late Thursday morning, bringing a gradual improvement in conditions.
This comes after what has been a dry September across Northern Ireland so far.
Parts of County Down have only had about 12% of the average rainfall.
The wetter areas have by in large been in County Antrim especially the Glens area.
Rainfall totals in the next 12 to 18 hours could mean make a big difference to the rainfall total for the month and some places may end up with a wetter than average September.
Meanwhile, rain is expected to cause disruption to parts of the Republic of Ireland on Thursday.
Met Éireann has issued a warning for Dublin and Wicklow from noon on Thursday until 20:00 BST.
The organisation is expecting rain to be heavy at times, with strong winds along coastal areas and on higher ground.
Residents are being urged to prepare for potential disruptions.
