UPDATE _ 3:30 pm Sunday
Showery rains across the southwest have now been joined by a generally lighter band of rain extending from about Wexford to Galway across parts of central Ireland. This entire frontal band appears to be slowly weakening and the general motion on it should be more northwesterly by this evening, so that some parts of eastern Ireland as well as Donegal and other northern counties may remain dry, with the exception of some parts of NI where thundery showers could develop in a separate cluster later on.
Looking down the road, the emphasis for Tuesday should probably be more to widely scattered heavy thundery showers with the second onslaught of the offshore frontal systems, as the latest guidance in particular shows quite a strong push of moisture into the warm air mass in place.
Looking quite thundery for the end of the very warm spell on late Thursday as well ... quite possibly for some, this warm spell or heat wave will be more of a heavy rainfall event (but locally, not on a large scale). However, looking at the current situation, I don't believe there is much more than an additional 5 mms of rain to come for most of the southwest, possibly 10 at the most.