A Status Yellow thunderstorm warning for counties Cork and Waterford came into effect from 10pm and will remain in place until 3am tomorrow morning.
Met Éireann issued several Status Yellow thunderstorm warnings over the coming days which impact most of the country.
The forecaster said there will be heavy showers with localised thunderstorms in both counties, with spot flooding and lightning damage possible.
A second warning has been issued for Leinster, Tipperary and Waterford, from midnight tonight until 2pm tomorrow.
The forecaster said there will be heavy showers with scattered thunderstorms across the region, and warns of localised flooding, lightning damage, poor visibility and difficult travel conditions.
A third Status Yellow warning for thunderstorms will also be in place for Cavan, Donegal, Monaghan and Leitrim, Roscommon and Sligo from 7am until 5pm tomorrow.
Met Éireann said that possible impacts will include localised flooding, lightning damage and difficult travel conditions.
The UK Met Office has also issued a Status Yellow thunderstorm warning for Northern Ireland from 6am until 9pm tomorrow.
It says heavy rain and thunderstorms will move northwards and may lead to some disruption in places, with counties Antrim, Armagh, Derry, Down, Fermanagh and Tyrone impacted.
Last Friday, ten cattle were killed in a lightning strike on a farm in Co Cavan.
The ten suckler-bred heifers, owned by a farmer from the Butlersbridge area, are understood to have taken shelter from the heavy rain under a tree in the middle of the field.
A bolt of lightning then struck the earth, killing them instantly.
