Flooding caused by heavy rainfall has resulted in a number of road closures and train service cancellations.
A yellow weather warning for rain across Northern Ireland expired at 15:00 GMT but it is having a knock-on effect on travel.
The Antrim Road near Belfast International Airport has been closed due to flooding.
Flooding has disrupted train services with the railway line closed between Ballymoney and Coleraine.
Translink said the 18:38 GMT Londonderry to Great Victoria Street (Belfast) service was terminated at Coleraine, "due to poor weather conditions earlier".
Further information on train services on Wednesday are available here.
The worst affected areas have been counties Antrim and Down but parts of Belfast have also been flooded.
The Carnreagh Road in Ballynahinch has been closed to commuters.
Some of the other roads that were flooded as of 18:54 GMT included the U1109 Dunadry Road, Station Road in Kells, and Bog Road, Ballymena.
A list of the roads affected are listed here.
Police have urged motorists to drive carefully.
Earlier on Wednesday, Belfast's Metro bus service experienced long delays.
#TRAIN Disruption to services on #Derry #Londonderry line due to #flooding. Latest updates for all train services this evening can be found here> https://t.co/rSxo2AxPs2 ^CD pic.twitter.com/pa4bvWxbHN— Translink (@Translink_NI) November 7, 2018
In south Belfast, flooding problems were compounded in the run-up to rush hour by a collision on the Stockman's Lane roundabout. It has been cleared, but it resulted in long delays for drivers heading towards the M1.
#ALDERGROVE: reports that the Antrim road near Belfast International Airport has been CLOSED because of FLOODING. This will affect those heading to the Airport from the Antrim direction(16.30)— BBCNI Travel (@BBCNITravel) November 7, 2018
Later in the week, an Atlantic system is expected to reach Ireland on Friday bringing more strong winds and rain.
A warning for both elements has been issued from 09:00 GMT to 21:00 GMT on Friday.