Central Pennsylvania has amazing outdoor scenery, which is one of the reasons it is such a popular wedding destination. Unfortunately the outdoors brings something else with it - the weather. No matter how you plan, you can not control the heat, cold, or rain on your big day - but you can be prepared for it.
If you are planning an outdoor ceremony or reception, discuss back-up plans with your venue - and do it when you first start planning, not three days before when a nor'easter or heat wave are just starting up. Have a plan for either moving things inside, having a tent, or including favors or amenities for your guests that will help combat the elements.
Also, don't forget about your Wedding Pros! Discuss with them how the elements might affect what they do. For example, live musicians might not be able to perform in certain temperatures or humidity conditions due to their instruments, while extreme heat may cause some electronic equipment to go into 'heat saving mode' and shut down if not under cover. Even if you plan to be safe and put everything indoors, ask your wedding pros if something needs to change in case of a blizzard, and plan accordingly.
Social media and your wedding website is a great way to also keep your guests updated in case of any last-minute location changes.
Bottom Line: You can't control the weather. You just can't. But being prepared and having back-up plans make everything much smoother. And if you do get unexpected weather on your wedding day, embrace it and have fun with it! If you stay calm and happy about it, the memories will be even more unique and special.