Heavy showers are battering the country since last night, with a status yellow rainfall warning in place for Munster and Leinster.
Spot flooding is already reported in areas of Dublin, Kildare and Kerry.
Met Eireann says that, while the heavy rainfall warnings are for Munster and Leinster, rain will be widespread over the rest of the country, giving a very wet and windy day.
The rain will clear eastwards later today, with temperatures ranging from 9C to 12C.
However, it will quickly turn cold during the afternoon.
Tonight will be cold everywhere as temperatures fall to near freezing in the early part of the night, with lowest overnight temperatures hitting 0C to 3C.
Tomorrow will be a cold day with strong westerly winds gradually easing.
Motorists are being warned to make sure their tyres are in good condition, with heavy rain being followed by a cold spell, with risk of icy roads.