Met Éireann is warning of thunderstorms and heavy rain with the ongoing risk of spot flooding for Saturday 21 August.
The status yellow warning is in place for Leinster, Cavan, Donegal and Monaghan.
This warning will come into effect from noon on Saturday and is expected to clear by approximately 8pm.
There will be scattered heavy showers and localised thundery downpours across these counties.
The heavy rain will bring an increased risk of spot flooding. The flooding and wet roads will create hazardous driving conditions.
The heavy rain and thunderstorms may cause a disruption to transport in some areas. However, many places will miss the worst of these thunderstorms.
There has also been a status yellow warning issued in Northern Ireland for Saturday 21 August. The warning is in place for Antrim, Armagh, Down, Fermanagh, Tyrone and Derry.
The warning for the northern counties will be in effect until the later time of 10pm, after which it is expected to clear.