Thanks, Andre. Forewarned is forearmed. If I make the tour I'm considering, I'll probably aim for May, maybe early June. The one time I visited The Holy Ground, some 40-plus years ago, the weather was benign, though it was late Feb., as I recall.
I enjoyed Eric Newby's Round Ireland in Low Gear, a funny tale and a very good read, but he made his trip in bits and pieces between September and March, as I recall, and I remember saying to myself as he began, "He must be bloody mad." In the same vein, early in Thomas Flanagan's splendid book on the '98, "The Year of The French", he starts a paragraph with this sentence, "It was one of those days on the West Coast of Ireland when the whole world seemed to have turned to water."
Gentle rain is OK; I don't much like cool-and-humid, and don't like a cold rain at all.
Cheers, John