Rain boots in Dublin in October?

I have never been to Dublin in October but it rains a LOT in Ireland. I am not entirely sure what you mean by rain boots - if you mean some sort of boot you would only wear if it was raining, I would say no. I would waterproof the walking shoes you planned to wear.

I visited in March, and I did bring a pair of wellies! They came with their own drawstring bag, so what I did was I wore them onto the plane, then once on board I took them off and placed them in the bag and then just carried them off the plane. I was very happy to have brought them since the first few days in Ireland it rained constantly and I enjoyed having dry feet. Watertight shoes would serve the same purpose, so those would work well too.

Have never been to Ireland, however - I have been to Wales and Scotland, and would have cheerfully knocked someone down in the street to steal their wellies (rain boots). I did have waterproofed shoes on, but enough rain pelted down onto my socks, and splashed up OVER the tops of my shoes, that on a number of occasions I had soaking feet within minutes of going outside. And there is little more unpleasant than trudging around, trying to enjoy the sightseeing, with wet feet. Also - wet socks and shoes makes your feet chafe more, and get blisters, etc. Given your tight space, maybe just buying a pair when you get into town makes sense. And it will be a cool souvenir!

Dublin (like most of europe) is made of cobblestones, and if you feel rainboots are you thing, go for it. There is a Mark & Spencers flagship store you can go shoe shopping. I wasn't looking for shoes but spent hours in that store.

Often times the pathways to castles and abbeys is grass...wet grass...we bought some Wellies there so we could walk thru the weeds and bogs. Great for the seashore too.

You will be most welcome to Ireland Patty. I have lived in Dublin for many many years and rarely if ever wear any kind of rain boots, watertight shoes or runners will be just fine. It rains much less in Dublin than it does in the west of Ireland. October is often a relatively dry month in Dublin as well. Hope this advice helps and that it turns out dry for you. Hope you have a great time here.