Ireland in August?
 

When is the best time to visit Ireland? August or September? We will be there for one week and traveling around by car. Thanks for your input.

August is peak season, September the Kids are back at school so things start to quieten down, accommodation frees up and the offers start. We head for Clifden Arts week towards the end of September which is one of the last big festivals of the season. October lots of the tourist sites are closing or closed.

Sounds like September is better of the two. If we go at that time it will be the first week of September. We fly into Shannon and want to travel the south area and then circle up to Dublin then back to Shannon. Does that sound feasible? Also would time permit to take a train to Belfast for one night?

I don't think that sounds like a feasible plan but I guess a lot depends on what you mean by "travel the south area".

I suggest you take a look at the AA Route Planner to see exactly how much time your proposed itinerary will be spent in the car. Add about 20% to the stated driving times to make them more accurate.

http://www.aaireland.ie/routes/

Consider Open Jaw (in Shannon out Dublin vice versa)if time is short. doing a loop to Dublin and back would probably need 10 days minimum if including a day trip up north. Or a week to do a northern loop up and over back down to Dublin.