Met Éireann have issued a yellow status weather warning as heavy rainfall is expected in 10 counties on Friday.
The warning which will be in effect from 8am to 8pm comes as heavy thundery downpours and localised flooding is expected Northern and Western areas.
Met Éireann say the warning will apply to all of Connacht and counties Cavan, Monaghan, Longford, Donegal and Westmeath.
Although temperatures are expected to remain in the low 20s, the national forecaster warns that 40mm of rainfall is expected in the North West of the country.