I know this will sound silly...

[Eastern]

For daytime in January at WDW I would plan on jeans and tshirt with a jacket or warm hoodie for daytime. In the morning/evening you will want the extra layer.

As it gets towards 1-2pm you'll feel warm and take your jacket off but you'll need it again after 3pm. You have to do layers in January. I have worn hat and gloves at Disney in January. You never know what the weather will do so I bring a lot. If you want to pack light, go in the summer.

 

[Jhondy]

We are going in 4 days and I’m packing jeans, t-shirts and zip up sweatshirts for me and my daughter. My husband is planning on packing shorts but I think he is crazy and going to get cold. We are from WI but I still think it’s gonna feel cool especially in the mornings/evenings

 

[Stratman50th]

Here's a snapshot of our forecast for the next week or so. You should look and decide for yourself. I can count on one hand how many times I've worn long pants in the last 5 years, LOL!
My wife still wears jeans when it gets in the 60s. Anyway, have fun.


EDIT: While this app is pretty good, especially the radar, any Florida forecast is only good for about 3 days....... maybe.