A severe weather warning has been issued by the Met Office across Northern Ireland.
A fireman pumps water from a flooded house in Rathfriland
It comes after hours of heavy rain caused flash flooding in parts of County Down on Thursday.
The warning says other areas will be affected throughout the early hours of Friday morning.
The Fire Brigade were called to Daisy Hill Hospital in Newry after fears of possible flooding on the site.
These concerns lessened when the water began to subside.
In Rathfriland, fire crews rescued a motorist who became trapped by the flooding.
A number of people also had to be helped from their homes in the town.
Water was pumped from several homes by the Fire Brigade.
Local residents described the rain as a "freak cloudburst".
They said the drains did not seem to be able to cope with the downpour.
Flooding was also reported in Castlewellan and Newcastle.