Pack a little of everything and prepare to layer. Jeans and t-shirts for the days, long sleeve shirts, heavy coats and gloves at night!
It can get very chilly in the evening after the sun goes down, ESPECIALLY at Epcot to watch Illuminations!
We usually start the day in jeans, tshirts, and sweatshirts. Get rid of the sweatshirts after the sun really heats up the day. By late afternoon sweatshirt is back on. By evening we usually add another layer(fleece jacket, heavier coat) and gloves. Don't forget socks and shoes...no sandles at night!~ Nothing worse then cold feet ! And this is from someone that lives in flipflops all year!
Some days MAY be warm enough for shorts but jeans are usually ok. And don't forget something to wear from the pool to your room if you plan to swim!