Hats are a must for me on hot sunny days or I will get a migraine. I've bought 2 baseball hats and a pink, wide brimmed hat on our trips.
Same here. I learned this the hard way during on a very sunny day in Disneyland several years ago. I spent almost a whole day of my 4 day trip lying in the dark in the hotel room as a result. Now I never go without a hat at WDW except on very overcast days but I always carry one with me just in case the sun sneaks out.