My best advice is to have a Plan B. There's no denying that we often experience hot, sunny days, but they are not a given, just because the calendar indicates that it's summer time.
Preparedness will keep your wedding plans on track and uplifted. Remember, it's not the weather that matters but the day of significance it holds for you and your loved ones.
It helps to have your wedding at a flexible venue, one that offers a lovely outdoor setting, with a just in case place to duck in out of an unexpected turn in the clouds.
Just take it as a test run for your marriage, you should make plans, but always be open to things that cause change.