Heavy rain and extreme winds have wreaked havoc across the country today, with gales of over 120km/h (75mph) reported in some places.
The west and north of the country have borne the brunt of the squally showers and heavy rains.
Galway city and county was battered by a thunderstorm this afternoon, while coastal regions are being pounded by high swells and strong winds.
Some 20,000 people are without electricity today after high winds brought down power lines.
The ESB said the worst affected areas are in Cavan, Longford, Monaghan and parts of the Midlands.
Motorists have been advised not to travel unless strictly necessary. The Dublin Port Tunnel is closed due to an apparent electrical fault and Stena Line and Irish Ferries sailings were cancelled earlier today due to the adverse weather.
Tonight's planned New Year's Eve party at Belfast City Hall has also been called off due to worries over safety after high winds were forecast. Up to 10,000 people had been expected to line the streets outside City Hall to see stars including Tony Christie, soul singer Beverley Knight and rock band The Thrills.
Met Éireann said the winds will ease this evening, although tonight will stay cold and windy, with clear spells and scattered heavy showers, with some hail or thunder possible.
New Year's Day is expected to turn cold with sunshine and showers. Some of the showers will be heavy and possibly thundery. Sleet or snow is possible over high ground.