January (winter in general) in Orlando is heaven. I made my first trip to WDW in January (I was starting as a College Program Cast Member many years ago) and I was in shock/love with how pleasant the weather was during the day (light sweater, or less) and the evenings (light-to moderate jacket). I'm from Atlanta, so it wasn't a massive (like Minnesota) difference, but it felt great to feel the warmth of the sun during the day and the chilly air at night. I don't remember much (any!) rain, either - I think January is a relatively dry month, too. Also, crowds are ridiculously low - I got very, very spoiled by the low tides that time of year and I expect to be quite overwhelmed with actually having to wait in lines during next month's trip!
You're going to have a wonderful time - hands down, it's my favorite month to go to WDW.