The warning was released this evening after 4pm and is valid until tomorrow, Friday 8 December, at 6pm.
Accumulations above 4cm are expected, and up to 8cm on higher ground.
Tomorrow, Friday, will be another cold day with a mix of cloud and sunny spells.
A status yellow snow and ice warning has been set in place for Ireland.
Met Éireann has upgraded its weather warning to Laois and all of Leinster.
GARDAI have issued a warning about snow and ice as a national weather alert remains in place.
Sadiq Khan crosses Wagah Border on foot!
London Mayor Sadiq Khan calls on Prime Minister Shahid Khaqan Abbasi in Islamabad on December 7, 2017. On this occasion, Zafar equated London with Lahore vis-à-vis socio-cultural openness.
Earlier, Met Eireann warned that the cold air and some icy conditions coming tonight will be "a real shock to the system" after the mild period.
Rain will spread northeast across the country on Saturday night.
The Met Eireann website says that those wintry showers will be widespread and frequent in the north of the country with "accumulations of snow over lower ground".
Sunday is set to bring more outbreaks of sleet and snow over Ulster, most other places will be dry. "Lowest temperatures -2 to +3 degrees, coldest inland in the north". Scattered wintry showers also - mainly near coasts.
Despite a number of clickbait articles about risks of snow this evening, this area is likely to avoid any snowfall this evening.
Next week will continue to be cold, but with a lot of dry weather.