Oh drat. With all the deals we’re doing our first summer trip this year and I’m trying to convince myself it will be fine once we hit evening, lol.
Let me start by saying I personally like summer weather at WDW. I like summer weather better than Jan weather.
How you feel about it sorta depends on your tolerance for heat and humidity. I don't mean that as negative as it sounds.
you didn't ask, but here are my pearls of wisdom after many summer visits:
Also, even in summer, WDW temps are not the same every day. They are maybe more consistent that other places, but there is still variation. So I have seen a few days when it was too hot even for me, but mostly it just feels like summer to me. I often find the weather especially nice following an afternoon storm.
In the evening, the temps do drop, and FL doesn't have mountains to trap the heat the way some other cities do. There is often a nice breeze.
IMO though, the key to a great summer visit is to take an afternoon break. It especially wise to take a break during afternoon storm O'clock. Know that many rides close during storms, and no swimming. If you like to swim or take shuttle boats, plan around any potential storms.
Another byproduct of the heat for me is that it tends to make me sleepy, especially after lunch. So again, a siesta works. IMO, it is also good if your lunch is a little on the later side and/or a little on the lighter side, and/or try to avoid high glycemic foods like french fries at lunch. On the other hand, having a scoop of ice cream for my lunch works pretty well. Also, sometimes a tiny bit of sugar is your friend. Overall though, one of the best things I find, is to keep eating produce! Lots of tomato, cucumber, Cuties tangerines, bananas, plus any other watery summer veggies I can find. (Ratatouille has long been popular for a reason!)
Fresh fruit is super. Also make sure to stay hydrated. Hydration packets are a decent option, as is electrolyte water. It is possible to drink too much plain water. I find I want a little more salt than normal. Sometimes a little apple juice and/or lemonade are the best options at WDW. Swimming and getting wet are good, but misters feel icky/clammy. I also wasn't a huge fan of the cooling towels, but they aren't expensive and don't cost much money. Some people like them.
Summer, for me, also requires a specific type of footwear. More or less, hiking/walking sandals that are water tolerant. You want something with a very good footbed (arch support), adjustable straps (for any foot swelling), a solid-traction tread (for walking on wet pavement). Some good brands are Teva (like the Hudson), Ecco (Yucatan), Dr. Scholls (Adelle, Gavin). I'm currently a big fan of the Dr. Scholls footbed. It molds like an orthotic insert to the shape of your foot, but you might find another brand/style is more to your liking.
I like to start the day early, and be out late. Do be mindful of the risk of hear exposure, and know the signs. When you feel a need to be indoors, get indoors, but generally, I really like WDW in the summer. It just takes a little adjustment.