A status orange weather warning is in place for much of the country with torrential downpours forecast.
The thunder warning has been issued by Met Éireann for Cavan, Monaghan, Donegal, Dublin, Carlow, Kilkenny, Laois, Longford, Wexford, Wicklow, Westmeath, Leitrim, Roscommon, Sligo, Cork and Tipperary.
Localised severe thunderstorms are forecast, with heavy rain and lightning strikes possible.
A lesser status rainfall yellow warning has been issued for the rest of Leinster, Limerick and Waterford.
Up to 5cm of rain may fall in short but heavy localised showers.
Both warnings will remain in place until 10pm tonight.
The Road Safety Authority is advising all road users to take extra care as poor weather creates potentially hazardous conditions.