A status yellow fog warning has been issued for all of Leinster.
The warning comes into place at 5am on Thursday will remain in place until 10am.
The AA advises road users who are driving in fog to use dipped headlights at all times with windscreen wipers and demisters on.
They have also warned people to be aware of other drivers not using headlights.
“Only drive as fast as conditions allow and maintain a greater distance between you and the car in front,” the AA added “Tailing someone’s rear lights can give a false sense of security and is dangerous.”
The warning comes as temperatures are set to drop below freezing throughout Ireland.
Met Éireann has said that while it will be dry, the temperatures will drop to lows of minus 2 to 3 degrees tonight.
The temperatures will rise slightly on Thursday with highs 4 to 8 degree.
Thursday is set to be a dry day but it will be “cold and sunny for western and northern areas".
The night will see temperatures drop to minus 1 while “dense fog will develop in places in near calm conditions”.
The rest of the week is set to be “cold and settled” with night frost making an appearance.
Met Éireann is predicting fair weather on the weekend, saying: “Most places will see a cold, dry and bright day on Saturday with afternoon temperatures of 6 to 8 degrees”.
The south will be milder with “scattered showers”.
The showers are due to linger in the south on Saturday but otherwise “it will be dry with a mix of cloud and clear spells”.
Temperatures will drop to around minus 1 while “mist and fog will form towards morning”.