A warning for thunderstorms and rain has been issued for 15 counties.
The status yellow alert will impact Cavan, Monaghan, Donegal and all of Leinster tomorrow.
The warning will kick in at midday and run until 8pm.
Heavy showers are being forecast with the chance of localised thundery downpours that may lead to spot flooding.
Meanwhile, the UK Met Office has issued a similar warning for Northern Ireland.
A yellow warning for thunderstorms has been issued for the whole region.