waves hi, I live in Dublin and I have previously lived in Galway and Edinburgh and visited Belfast.
Temperature wise, it is usually between 65 F to 75 F, with 75 F being a heatwave and usually only last 2 or 3 days. I always have sunscreen, sunglasses and an umbrella in my handbag at all times. For example yesterday Saturday 3 June, I left my house at 11am and had sunscreen on my face and wore sunglasses, but the temperatures had dropped by 3pm and it rained heavy showers on and off for the rest of the evening.
My summer clothes are usually jeans and a tshirt with a hoodie. You will see all sorts of attire though, for example if its 70 F you might find it chilly and wear a sweater and jeans, while locals are wearing clothes you think are more suited to 90 F temperatures.
You will do ALOT of walking so make sure you have proper footwear, think like going to a Disney park.
For your electrical appliances you will need a US to UK plug adaptor. In UK and Ireland we have a 3 prong plug. Also you may find your USA hairdryer for example does not work as well as it does in USA.
You should also be aware that in UK and Ireland we use chip and pin as standard on our debit and credit cards. This includes everything from ATMS, to department stores, small grocery and drugstores, to restaurants, theatres, cinemas, train and bus stations and even some taxi cabs, and all self service ticket machines. Some Dis posters have said that they can no issues using their swipe and signature USA cards, but just to be aware that in areas where they may not get alot of American visiters you MAY have issues with your signature only cards.
While PP recommended The Westin, as a local there are other more reasonably priced hotels I would recommend. I know Disney use this hotel for
ABD but honestly, in my opinion its over priced for that location. Also the restaurants PP recommended, they are on the upper end of the fine dining and honestly you can find just as good food in many other restaurants, without the paying such exorbitant prices. Now of course if fine dining is your thing and you have no problem dropping hundreds of Euros for your evening meal every day of your time in Dublin, and want to be part of Dublin high society and be seen and possible feature in the society pages of the Irish media, then of course book at table in Patrick Guilbaids or LeCrevain for every night of your time in Dublin.