A Status Yellow rain warning has been issued for seven counties by Met Eireann; the warning is set to be valid from later this evening.
Counties in the Munster region, as well as Galway, are subject to the rainfall warning. There will be a danger of between 25mm and 40mm falling in these areas over the course of a 12-hour period.
Showers will merge into longer spells of thundery rain, according to Met Eireann. Surface water and spot flooding will also be likely, it added.
For the start of 2018, rainfall accumulations have been around normal for the bulk of the country, Met Eireann explained. Values for the last seven days are measuring close to 100% of the average, it said.
However, the weather is set to become wetter over the weekend and during most of next week.
“A very active frontal zone will bring heavy rain through Friday night and most of Saturday too. A strong polar maritime airflow next week will also result in large amounts of rainfall from heavy showers and outbreaks of showery rain,” the Irish meteorological office said.