Met Éireann has issued two rainfall warnings for several areas around the country.
An orange alert is in place for Connacht, Donegal, Clare, Cork, Kerry, Limerick and Tipperary - with forecasts of widespread, heavy rain, with some thundery downpours.
It says these will develop Thursday night and through Friday, leading to spot flooding and possibly accumulations of up to 50mm - but with up to 70mm on high ground and on mountains.
Meanwhile a yellow alert has been forecast for Leinster, Cavan, Monaghan and Waterford.
Met Éireann says heavy rain falls will develop during Friday and Friday night, leading to spot flooding.
It is warning of possible accumulations of 25 to 35mm, with the alert in effect until 6.00am.