An unsettled week of weather lies ahead with temperatures dropping to -2C and wind gusts reaching up to 100kmh.
Met Éireann has issued a yellow wind warning for four counties, Donegal, Leitrim, Mayo and Sligo.
The warning will remain in place until 6am this morning. It also issued a status yellow gale warning on coastal waters.
But it is the sharp frost and plunging temperatures tonight that are likely to prove the biggest shock.
Temperatures will then return to double figures by the weekend, although it will remain unsettled as the week goes on and sunshine may be in short supply.
Last night was expected to see widespread and wintry showers, becoming increasingly blustery especially in Ulster which was very windy along coastal areas.
Lowest temperatures of 1C to 5C were forecast overnight with showers clearing towards the morning.
The wind is set to continue this morning with fresh north-west winds, but will ease through the afternoon.
It will be a dry and sunny day with highest temperatures of 7C to 9C.
Tonight will be cold with a widespread sharp and severe frost and minimum temperatures of -2C to 1C, with light breezes.
It will be mostly dry tomorrow but rather cold, with moderate southerly winds with highest temperatures of 7C to 10C.
Temperatures will just stay above freezing tomorrow night, although frost may form in parts of Ireland, with temperatures dropping to between zero and 5C.
On Thursday, it will be mainly dry and cloudy with highs of 9C to 11C with moderate southerly winds.
Friday will start out dry but rain is expected towards the evening. As the day goes on, there will be mild winds over most of the country, with highest temperatures up to 12C.