A rainfall warning for Leinster, Connacht, Cavan, Monaghan and Donegal has been issued by met Eireann today.
It says a spell of heavy and locally thundery rain will move westwards across the country, from the Irish Sea, this morning and during the afternoon.
Some intense downpours can be expected at times, says the Met Eireann warning, with totals of 30 to 40mm are likely, highest over Leinster, where values on some mountains, may get up to 50mm.
The warning is valid until today at 6pm (Sunday, August 23).
There will be further heavy rain for a time overnight in parts of Ulster, but good dry periods in many other areas, with scattered heavy showers especially in western and northwestern counties.
Unsettled and cool conditions through the week.
According to Met Eireann, it will be cool and bright tomorrow with sunny spells and scattered heavy showers. Windy at first in coastal fringes of the west and northwest but winds easing there in the afternoon.
On Tuesday, it says some bright dry weather during the first half of the day in midland, northern and eastern areas, but rain will become widespread through Munster and Connacht and then extend to remaining areas later in the day.
Wednesday will see a reasonably bright day, according to Met Eireann with sunny spells and scattered heavy showers, but there is a risk of cloudier conditions in the parts of the south with more persistent rain there for a time early in the day.
Bright on Thursday also, it says with sunny spells, but showers becoming widespread and heavy in places in the afternoon, especially in midland and western areas.
Met Eireann says current indications suggest it will continue unsettled through Friday and Saturday, with some further heavy showers at times but some dry bright weather also and afternoon temperatures in the mid to high-teens.