Having just finished a wedding last weekend, I can reflect back on all the off season weddings I have done over the years. One key item... have a back up location if you wanted to have your ceremony outside. Or your reception for that matter.
Historically, there has been about a 90 percent success rate in having your wedding outside, at least with me, and not having your event rained on. Magically it seems that it stops raining just when you need it to and then it absolutely pours afterwards. Last Saturday was no exception, but the bride and groom decided to go inside just in case.
For sure expect to have wet chairs or expect your guests stand for the ceremony. Just in case you can always invest in umbrellas for them and even make it part of the event by choosing bright or fun colors. Makes a pretty backdrop for your wedding too.
Good luck on your wedding day.