The humidity is lower right now, and it’s MUCH cooler than even a week or so ago. If you need the weather to be under 82 or so, you may never find a day go to to WDW. But it’s not that bad when it’s warm. There is some shade air conditioning in all the indoor areas, etc.
Weather is variable, too. Last January, for an entire week it was really really cold, like 24F at night and the pools had to close several times because they couldn’t maintain the chlorine properly that cold. When it was open, my Wisconsin grandkids swam and swam but got cold when the came out. I was in hat, mittens, north face jacket and a scarf and freezing (must have been less than 50 degrees). It can get quite hot in late October (two years ago it was about 90+ I think) or cool and 60s. But usually 80 is pretty comfortable as long as you drink water and rest when you want to. I’ll even take off my sweatshirt if it gets above 80.
I will say that last summer when it was in the mid 90s with 90+% humidity that I did bring a cooling towel for my neck and went in the mister by GoG. Hollywood Studios seems much hotter to me than AK or MK, and parts of Epcot with all the concrete can feel hot, but there is always shade and a cool place to go.