Hi Yvonne! Walt Disney World is a very casual place, so you don't need to worry about dressing up. Just be sure to wear comfortable shoes because you will be walking a lot. Only the signature restaurants have a dress code, and it's a fairly relaxed one. You can wear shorts and t-shirts to the signature restaurants, but not tank tops, torn clothing, swimsuits, or cut-offs. Likewise, in the parks, you cannot wear costumes or clothing that is very revealing. (Click
here to see the official policy.) You'll see some guests at La Nouba who are dressed up, but others will be in shorts or jeans.
During the winter at Walt Disney World, it can be chilly at night and pleasant during the day, so you'll want to plan to dress in layers. It may be warm enough for shorts and t-shirts during the day, but you may need a coat in the evenings. I'd recommend that you pack a variety of clothes: jeans or long pants, a few pairs of shorts, short-sleeved shirts, cardigans or sweatshirts and a coat so you'll be prepared for various temperatures. The pools at Disney World are heated in the winter so you'll be able to swim or visit a water park if you want.
Because winter high temperatures average in the low 70s during the day in Orlando, snow is not normally an occurrence, except at Mickey's Very Merry Christmas Party!
Come visit us again at the Moms Panel if you have more questions! We'd love to help!