They are forecasting north, northwest counties and areas on higher ground to be the worst affected but the entire country is at risk of snow.
The warning was released this evening after 4pm and is valid until tomorrow, Friday 8 December, at 6pm.
Met Éireann has upgraded its weather warning to Laois and all of Leinster.
Forecasters warned that "significant falls of snow are likely to cause accumulations of 3 cm or greater above mean sea level".
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Russian Federation and China have also called on a halt in the joint exercises as part of a so-called " double freeze " plan. Pyongyang has said the drills prove that US President Donald Trump is " begging " for nuclear war.
The public has been warned to beware of icy roads and footpaths.
Maximum temperatures 6 to 9 Celsius early on, but it will turn much colder, with strong and gusty winds up to gale force along northern coasts.
Met Éireann says these areas can expect occasional snow showers on Thursday evening and during Friday with accumulations of up to three centimetres in places.
"There will be a cold spell for the next ten days". It'll stay cold, but bright. Frost may linger in places and temperatures at best will range 1 to 3 degrees. There may be a light dusting of snow around the country, and it may stick in places in the north and northwest.