Can be a "mixed bag". Last year it was nice, there were those last days of lower humidity before "summer" hit, low 80's, but sometimes it can be warm and humid and rainy. We've had another year when it was extremely hot with no rain. And another year of wildfires which created some nasty smoke in the area for a few days..hoping that won't happen this year but we've been "low" on the rain gauge in FL lately.
We've been to WDW several times in late April, early May (as a matter a fact we'll be there next month then too!) This is usually our last trip before late summer or early fall. Just keep your eye on the forcast, hopefully it'll be like last year which was mostly nice.