Met Éireann has forecast that parts of the country could experience the first snow showers of the winter tomorrow night.
Hail, sleet, and possibly snow is most likely in the north and west of the country but the forecast is for sharp to severe ground frost in all parts of the country on Saturday night.
Rain will spread rapidly across the country on Sunday, but strong winds will keep it feeling cold, despite an increase in temperatures.
That should make for challenging conditions at Lansdowne Road on Sunday afternoon where Ireland take on Australia in rugby.
A capacity crowd of 49,000 is expected to attend the game, and normal restrictions on traffic and Dart services will be in operation.
The domestic soccer season draws to a close this evening with the title-deciding games taking place at Tolka Park in Dublin and the Brandywell in Dublin.
Shelbourne will win the Eircom Premier League as long as they can match or better Derry City's result against Cork. The Dublin side face city rivals Bohemians, and all matches kick off at 7.45pm.
Elsewhere around the country, further events will be held to mark Science Week, which draws to a close on Sunday.
There are some roadworks taking place that could cause traffic disruption on major routes. There are traffic restrictions on the M7 southbound between Maudlins and Newhall today to allow for essential repairs, but they should be lifted by 4.30pm.
Delays of up to 30 minutes are also likely on the N7 at Mountrath during peak times, and motorists advised to take an alternative route via Durrow and Borris in Ossory.
Motorists in Castlebar, Co Mayo, should allow extra time to complete their journeys today as conferring ceremonies at GMIT Castlebar and a series of roadworks around the town are likely to cause delays.