A few years back,3 or 4 maybe, the weather prediction for the week was for awful weather and there were cancellations because of that. That week turned out to be the best weather I can remember in 31 years!
No guarantees but even with rain in the forecast it doesn't always mean all day. My friend is coming with me for the first time and when he asked me about the weather I just said bring a ran suit, hot weather clothes, cold weather clothes and be prepared for anything in between but most of all come with a good attitude and you will have a great time.
Take care, Mike