Does it rain in Dec/Jan? Yes (and also occasionally snows). It's not nearly as common as the almost daily afternoon showers Florida get's mid summer. Going that time of the year, I'd buy a couple of cheap dollar store ponchos to throw into you pocket primarily for the water rides and figure throwing them away after a ride or 2. If I was going mid summer I'd consider springing for a more durable poncho that's more comfortable.