First off, the weather forecast looks a bit mixed. There is likely to be rain in the morning as a front passes over but it should be largely out of the way by the time the race starts. Behind the front, there will be strong westerly winds which will keep the temperatures in the low teens. There may be a chance of showers at race time but hopefully, the worst of it will have passed. All going well, it will hopefully be just overcast, mild and windy.
In the past, the Dungarvan 10 has been noted for freezing cold winds. Not this time around. If you are racing then a singlet or a short sleeve dry fit top should be enough.
As for the course, it is the same as last year which involved some changes. The updated preview can be seen here... http://munsterraceroutes.blogspot.ie/2013/03/waterford009.html
The course map is shown below. The strong wind is likely to be a factor betweens miles 1 & 2 and 3 & 5. It will be behind the runners for a lot of the course.