Help!

This is not the posted I intended to start off my post vacation, but that is the way things went. I had an amazing time in Southern Utah, going on bike rides, playing in the park, and enjoying the 70-80 degree weather. Then I had to come back to the uncertainty of Northern Utah, with it's 40-50 degree weather and looming storms. Here is where I need your help. My son's first birthday celebration is TOMORROW, and it is supposed to rain tonight and lightly snow in the morning. It may or may not be done by afternoon. I have planned the party at 6pm, OUTSIDE under our pavilion. It is covered, but the temps will only be about 45. I DO NOT have an alternate location and I invited too many people to have it at my small condo. WHAT DO I DO? Has this ever happened to you? To say I am stressed is an understatement, I have put a lot of work into this party and really wanted to have fun celebrating my baby's first year. I need some advice, any suggestions, even if you just tell me I am hosed. I hope to have some pictures to share with you later in the week, but who knows! Also, there is no way to move the date of the party, I work nights the rest of the week including the weekend. HELP!