Hi Ana,
Your trip is so very close & I know you're super excited! You can check the 10-day weather forecast on
www.weather.com (this is the website for The Weather Channel).
I checked the 10-day forecast for Orlando which only goes through December 14th. Right now it looks like the highs will run between 65 & 77 degrees Fahrenheit & the lows running between 39 & 53 degrees Fahrenheit. There is also a 60% chance of scattered thunder storms on Sunday, Dec 14th.
Keep an eye on on the forecast up until your trip as weather models can always changes. So it looks like you're going to have some nice days but chilly evenings so be sure you pack accordingly.
If you ride Splash Mountain or any of the other water related attractions, there is always a chance that you'll get wet. I'd try to ride any of these attractions mid-afternoon when the temperatures will have reached their highs for the day.
I'd also suggest wearing a poncho. We usually buy some cheap ones that we can toss after one use. If you decide to go with more expensive ones, be sure to bring a plastic bag to put them in once they are wet. Make sure you take them out to dry when you go back to your resort so you don't end up with mildew or musty smells. You may want to bring a pair of flip-flops to wear during the ride & put your other shoes in a plastic bag for protection.
I don't like to walk around in wet clothes (unless its really hot or I'm at a water park). If you're like that, you may bring a change of clothes. If you don't want to carry all this stuff around, you could always rent a locker to store it in.
If you have cameras or other items that you don't want to get wet, may sure you bring a ziploc or some other plastic bag to keep them dry. Wishing you many magical memories :-) Allison