The 52-year-old was a passenger in the car which crashed at Kilsallagh, Co Mayo, at 12.35am. He was pronounced dead at the scene.
He is the third person to be killed so far this year.
Gardai said the 23-year-old driver and a second passenger, aged 19, were not injured.
The road is closed for a forensic collision examination and diversions are in place.
Motorists have been warned to beware of black ice and gale-force winds over the coming days.
Met Eireann said stormy conditions will develop overnight with damaging gusts of between 100kph (62mph) and 140kph (87mph).
They will be strongest in Connacht and Ulster, where they will occasionally reach violent storm force 11 between Bloody Foreland and Fair Head.
Gardai have also appealed for witnesses to a New Year's Day crash at Inane, Roscrea, Co Tipperary.
Two women were injured when their car hit a grass verge on the old N7 at 4.40pm.
They were rushed to Limerick Regional Hospital where the driver of the car, a woman in her 50s, remains. Her passenger, a woman in her 80s, was discharged earlier today.