We just bought a pack of ponchos for our trip. The ones in the park are so expensive and it is guaranteed to rain, no matter the season, in Florida. Buying them in advance is not very expensive and I would rather be safe than sorry. no one wants to be stuck in the rain with out some form of perfection from it!
They do make shorter sleeve ones! I can't post links yet, but if you go to amazon dot com /Juvale-Count-Adults-Rain-Ponchos/dp/B018THPISO/ for example, there are ones that are about elbow length. For years, this was the only kind I ever found for a reasonable price around my area, so I've used them many times. They are great for warm rains.