Met Eireann are forecasting two big drops in temperatures on Thursday and Friday night as a winter chill hits.
The forecaster is expecting -2C on Thursday night with -1C conditions the following night.
A Met Eireann forecaster said: "Cold and calm tonight with further frost and fog. The fog will be dense across parts of the midlands and southeast.
"Staying dry across most areas, except in the northwest, where increasing cloud will produce patchy drizzle. Minimum temperatures of -2 to +3 degrees Celsius, coldest across the Leinster and Munster.
"Cold overnight Friday and turning frosty for a time with patches of mist and fog also. Becoming a little less cold later with scattered patches of rain and drizzle spreading from the south. Minimum temperatures of -1 to +3 degrees, occurring early in the night with light or moderate east or southeast breezes."
And it comes as 12 counties remain under fog warning until 10am on Thursday.
All of Leinster is at risk of dense fog with Met Eireann's yellow warning in effect.
Luckily, temperatures are expected to improve considerably next week with plenty of dry weather expected too.
The forecaster added: "Current indications are for high pressure to remain positioned close to Ireland for Monday and Tuesday bringing mostly dry weather but with some scattered patches of rain and drizzle.
"Daytime maxima generally ranging 7 to 10 degrees with night-time temperatures of 3 to 6 degrees. Winds will remain mostly light, varying in direction."
