Ireland Trip

At the recommendation of Dublin friends we went in late May. Rhododendrons were in full bloom, only one day of real rain, full-blown tourist season had yet to begin. Only downside was that the more formal gardens were not in bloom yet.

We visited just the western side of Ireland, but found it fabulous in late August. Weather was generally pleasant, but two days of very light showers and windy on other days....but guessing that is pretty typical.

May thru August is usually the safest bet weatherwise. Will be a bit warmer then, making it more pleasant to be outside even if you do catch the occasional passing shower.
Since the big tourist influx begins around the 2nd week in June when schools let out my suggestion is May - historically the sunniest month of the year for most parts of Ireland, and early enough in the season to avoid the crowds at the more popular attractions.

I've been once in May, supposedly the driest month. I'm going back again this May. Last time there was only a small amount of rain; nothing that disturbed our plans. We'll see how it is this time?

I've made two trips to Ireland, both in September, and the weather was fine. There was what I would call rain (being from Oregon, I wouldn't categorize drizzle or a few showers as a proper rain) on one day on the first trip of 15 days and two days on the second trip of three weeks, but generally the weather was lovely. It was a bit on the cool side but not so cool that a coat was required--a heavy sweatshirt was sufficient. And the added advantage to September is that things are all still up and running but there are fewer tourists around than in the high season.