Windguru is worth a look in terms of seeing what sea conditions will be like for upcoming events:
http://www.windguru.cz/int/index.php?sc=47735
You can change the wind speed to knots from the beaufort scale with the 'knots' link.
For example, this Saturday in Kilkee it's looking like a force 3, south-southeast.
Rain predictions by windguru are questionable at best, but wind is good. One piece that can change are if weather fronts speed up or slow down, so if it's predicting something bad 7 days away, that could change to 6 days out or 8 days.
Tides can be seen here for most ports http://easytide.ukho.gov.uk/EasyTide/Ea ... tPort.aspx
Again, Kilkee isn't listed but points north and south of it have low tide at 11:30 - 11:40am. The significance of tides comes into play more if you're in the water in the middle 2 hours of the 6 hour period between low/high tide - water generally moves fastest then. Spring tides (full moon/no moon) have the biggest variance between low and high.
There's data buoys around the coast for detailed information on current sea conditions, http://www.marine.ie/home/publicationsd ... ations.htm but probably more useful for organisers deciding on whether to go ahead with an event. Do you really want to know how high the waves are out there?
Finally, there's http://www.met.ie/. Have a look at the sea area forecasts here. It's good, but in Galway we used to joke that they were predicting 20 miles west of Dublin when referring to the West
Regardless of what is predicted though, local knowledge is hugely important. Don't assume something will be cancelled as sites can be sheltered from weather coming from certain directions. I've dived in a force 8 in a sheltered bay - problem was trying to get changed afterwards
Dave