Given today's headlines, I'm not sure anyone can really say what this upcoming August will be like at WDW.
Even if the virus completely abates, it now appears we could well be feeling the repercussions for a number of months.
I have a feeling this event is going to throw WDW crowds off from what they were last summer, and it is anybody's guess. People often plan their trips well in advance, if the stock market keeps up like it has this week, many folks are likely to skip trip planning. Keep in mind, many of WDW's past summer visitors have come from outside the USA.
So people may well put off vacations.
On other the hand, people might postpone, the major airlines and WDW are likely to offer discounts, and come August we could even see above average crowds as people try to put this event behind them.
The one thing that isn't likely to change much is the weather. August is hurricane season. Beyond that, it often rains most afternoons. Sometimes rain is short, other days it lasts all afternoon. Often it comes in heavy downbursts, and has lightning. Lightning = pools, coasters, animal attractions all stop (temporarily) and shuttle boats stop running.
And I should add, WDW takes precautions if lighting is within a certain distance. It might be perfectly sunny over the pool when it closes.
I think it generally pays to plan for possible rain, humidity, and 90 degree heat. Some folks don't mind 90 degrees, others find it uncomfortable, and it often makes people sleepy. One key thing to summer trips is to make sure everyone drinks plenty of water!
For us, that often = taking afternoon breaks. other times of year we don't take them, but in summer we do. If no rain, a good thing about FL in summer is that there are no Mountains to trap the heat, so temps cool down a bit after dark. If the parks are open late- not a given at all anymore - then returning after the storms pass can be worthwhile.
On other thing we try to limit in August is eating in the World Showcase. I like the WS eateries, but it is impossible to arrive dry if there's a downpour. For August dinners, the hotel eateries are better, assuming you have a car or are willing to take Uber. If you choose a monorail resort, you get access to all the monorail options via monorail. Eating at your home resort is also a good bet. Any hotel with indoor corridors is good choice.
We also tend to favor arriving as early in the AM as possible.
I also favor staying as dry as possible for as long as possible. (Either that or get VERY wet in the pool!) Some people use misting fans, but I think they just = clammy. Summer musts, IMO include: deodorant, sunscreen, water tolerant walking sandals, and rain gear. on days w/ rain odds over 50% we carry an item called a 'packable rain parka' - at least that's what Uniqlo calls theirs. Many stores sell them though under different names. the key feature is that they fold down into one pocket. On days when rain is less than 50% odds, we carry plastic ponchos -compact, but lousy in 90 degrees.
For long hair, ponytails and braids are good. Take pics in the AM before faces are glossy/hair stringy.
We also minimize what we carry into the parks: water, rain gear, Chapstick style sunscreen, maybe a small snack, and that's about it. Heat+ heavy backpack is bad combo. Oh, and be careful about chocolate! All the theme parks sell it EVERYWHERE but it melts very easily. After dark is good time to buy, or else eat it right away. other foods are also quickly perishable in heat.
Despite all the warnings, I actually like the FL theme parks in the summer. If no rain, then afternoons in the pool are very fun. Just don't assume it will be an option every day.