Hi Kelley,
Turn that frown upside down! I just checked the last weather forecast for Disney World on
www.weather.com. The current prediction shows scattered and isolated storms on Monday & Tuesday with the chance of rain at 30%. That means there is a 70% chance it won't.
I like to be prepared just in case so I stock up on inexpensive rain ponchos before our trip. They're small and I put several in my backpack. If it rains, we put them on & go as long as its not thundering. When it stops we toss them so we don't have to keep up with wet ponchos. If you are traveling with a stroller, be sure to bring a raincover for it. If it even slightly looks like rain when you park it before heading into an attraction, cover it. I also pack umbrellas that fold up small enough to fit in my backpack & carry a plastic bag to put it in when it stops. If you forget to pack ponchos or umbrellas, they do sell them in the parks but expect to pay more.
Fortunately, a lot of queues are covered at the Magic Kingdom so once you get in line, you should be okay. If you see that it looks like the rain may be setting in for awhile, head to the Country Bear Jamboree, Carousel of Progress, Monsters, Inc. Laugh Floor or the Hall of Presidents. There is also an arcade at the exit of Space Mountain tucked behind the gift shop. This is a great place to wait out the rain.
It looks like the temps will be nice during the day so I'd wear light clothing in case you get wet so that it will dry faster. I also wear sandals on raining days if its warm so that I'm not walking around with wet feet. You could also bring a change of clothes and rent a locker to store them in just in case.
Let us know if you have any other last minute questions. We're hEAR for you! I'll keep my fingers crossed for you. Wishing you minnie magical memories :-) Allison