Heavy rain is due to affect the north until Thursday after an amber warning was issued and motorists advised not to travel due to risks of flooding on roads.
The Met Office amber warning for most of counties Down and Armagh began on Monday evening and remains in place until 9am on Tuesday.
A yellow warning for heavy rain will stay in place for the rest of the north until noon on Tuesday, and from 9pm on Tuesday evening until 9am on Wednesday.
The arrival of Storm Ciarán has prompted a yellow warning for most of counties Antrim, Down and Armagh, which will remain in place until midnight.
For Tuesday's amber warning - the second highest level below a red warning - the Met Office has said fast flowing floods could present a "danger to life", and warned of structural damage to some buildings, possible road closures and disruption to travel services.
Police advised the public not to travel before 9am on Tuesday if possible.
On Monday, flooding led to road closures in counties Antrim, Down and Armagh.
The Department for Infrastructure said heavy rain over the weekend has caused ground saturation that will "inevitably lead to more localised flooding".
"The Department for Infrastructure’s roads and rivers teams have been checking and clearing road gullies and drainage grilles and additional staff will be on standby," a spokesperson said.
"Monitoring of water levels and tides has been ongoing and will continue until the weather warnings have elapsed."
The Met Office said of Thursday's yellow warning: "Rainfall amounts are likely to reach 20-30 mm widely, with 40-60 mm accumulating across high ground. Strong northeasterly winds may exacerbate any impacts from the rainfall."
