Widespread flooding has led to road closures in Co Fermanagh.
The A509 between Belnaleck and Derrylin is closed at Thompson's Bridge and a diversion is in operation via Fivepoints and Kinawley.
The Dernawilt Road at Killyfole and the Inishmore Road at Inishmore have also been closed due to flooding.
The roads were closed overnight on Thursday.
In Co Tyrone, the Favour Royal Road between Augher and Augnacloy at Cassidy's Bridge has also been closed.
Police have issued a warning about the Airport Road between Glenavy and Crumlin, the Belfast Road between Templepatrick and Antrim and the Crumlin Road in Glenavy.
Warning
The PSNI has advised motorists to exercise caution and drive with extreme care after exceptionally heavy rainfall across Northern Ireland caused widespread flooding on many roads.
Motorists are being advised to reduce their speed, use the appropriate lighting and drive with care.
The Met Office has issued a severe weather warning for Northern Ireland, due to the heavy rain and strong to gale force winds.
Forecasters said there could be up to 40 millimetres of rain on high ground so the risk of localised flooding is high on Thursday.
"Northern Ireland is going to have unrelenting rain for the entire day and into this evening and overnight as well," national forecaster for the Met Office Nigel Boulton said.
"Many places across Northern Ireland could see up to 25 millimetres of rain on low ground and we could see another 35 to 45 millimetres over the hills such as the Mournes, the Sperrins and the Antrim plateau as well.
"This rain will be falling on already saturated ground so this does mean there could be some flooding problems locally as time goes on."
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