We went during Mardi Gras this last february and I just about froze my tookus off! OMG it was COLD! Confisco had a booth removed and a ginormous heater with a blower in the spot where the booth was supposed to be! (It looked like a mini-jet engine with a heater inside! LOL!)

I had only packed a light hoody and one or two of my shirts were long sleeve. Needless to say I lived in that hoody for a few days and my long sleeve shirts DID get worn more than once! LOL!
But this is NOT the norm. Seriously...orlando was NOT equipped to deal with that cold. We saw space heaters in businesses! LOL!
If it is nippy while you are there, definately dress in layers! It might start out near freezing (If it's a freaky winter like last year) and be short sleeve weather by lunch. Florida weather has a mind of it's own and doesn't really follow the *guidebook* for how weather is supposed to act.

(But we're used to that...we're from Louisiana...

)
If you pack for 2-3 days cooler weather you should be fine as you'll probably be taking the layers on and off and able to re-use them later inthe week. Since I'm from Louisiana, *cooler* can mean downright cold to me....up north it means *sweater weather* normally...but don't forget that *Florida Cold* (on the rare occasion when it's THAT cold) is a particularly bone chilling kind of cold because of the humidity. And when we were there it was pretty windy. (But I have the best DH in the world...he knows how poorly I tolerate cold and always lets me use him as a wind screen.

) I'd suggest a light windbreaker as a jacket and some warmer stuff (light sweater...long sleeve shirts, etc...) underneath.
And about the water rides inthe winter.... *I* did the barges on a warmer day (still cold to me, but DH had his heart set on riding...it's our favorite...) and stayed *relatively* dry with a poncho. (The back of my shirt/hoody was soaked on the bottom...and the top of my pants, but since aI was in a wheelchair by that point, it stayed warm...LOL) DH on the other hand has this AMAZING ability to go on raft rides and stay perfectly dry! He rode it 2-3 times and was still dry.
Enjoy your trip. Even though it was cold, the weather was beautiful in February! And the ccrowds were SOOOOOO low!!! Even during Mardi Gras when half of Louisiana was there.
