what is the weather like? supposed to be one of the more sunny and dry months research says temps in a range of 45-60 F and yes of course, we are going to layer, layer, layer...and pack rain gear
Think of the damp factor too, even if it isn't raining, it can get into your bones (sort of like the Pacific NW). As already mentioned, layers are the trick.
May does have the potential to be sunny and warmer. I think it is a lovely month to be here. Probably best to check a few days before you leave.
You are 100% on the clothing! I moved over here from Atlanta 3 years ago and I still layer :)
Go in expecting the worst and you may be pleasantly surprised when it doesn't happen :)
A good weatherproof coat, comfortable boots or waterproof shoes and a couple of layers will get you through almost anything.
We went to Ireland in late May several years ago and it was very cold and rainy.Peat fires were still going in pubs. We were unprepared clothing wise so do plan for layers and a warm jacket.
Unlike an earlier poster, when I went in the last two weeks of May 2008, we had sunny skies almost every day. Shows how unpredictable Irish weather can be.
As others have suggested, bring layers. You don't need to dress for winter weather, just fall. You'll want light layers as well as heavier ones in case you get some warm days.
Where are you going? That makes a difference as well.
We went the end of May last year. I most always was wearing a jacket and scarf. At the cliffs of Moher it was freezing - everyone there was caught off guard. Thankfully we had stocking hats as well. Rain was unpredictable as well.