It comes after the Met Office advised of strong winds of up to 70mph this weekend.
The yellow alert is in place from 7am this morning.
Forecasters have warned it could affect Christmas travel plans.
Windy weather is hitting Northern Ireland today. Stock photo.
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The Met Office said “Strong westerly winds are expected to develop through the course of Saturday, with gusts of 50-60mph developing quite widely across this region, and a small chance of gusts reaching 70mph around some coasts and high ground areas.
“This has the potential to cause delays to public transport and some disruption to the road network, which may have a greater than usual impact given the busier pre-Christmas weekend travel.
“Dangerous coastal conditions can be expected too, with large waves an additional hazard.”
Today’s warning is in place for counties Antrim, Down, Fermanagh, Londonderry and Tyrone.
It also affects Scotland and northern parts of England and Wales.
Meanwhile, a second alert is in place for Northern Ireland on Sunday, amid warnings of prolonged strong winds.
The Met Office added: “Strong and gusty northwesterly winds are expected to develop on Sunday.
“Gusts of 50-60mph are expected quite widely, and around some exposed coasts and hills of gusts 70mph are possible, especially in the north and west.
“In addition, squally showers are likely with some hail and thunder possible in places.”
The alert is in place for all six of Northern Ireland’s counties, running until 9pm tomorrow.
