|My practice is to tour my garden at the hottest time of day to check for plant distress. Most of my plants have no problem with 100 degree weather.|
Plants show heat stress in various ways, so you need to educate yourself. But wilting is an obvious sign, and any departure from the normal should be a warning. In some cases leaves undergo a subtle change of color or shape. Examine especially any new growth. That's where the stress will be most evident. I don't like to see any mature tree wilting, so if that happens, I take action immediately.
Water any plant in distress. If signs of stress are serious, hose down the plant at length with the nozzle on "shower," then do it again an hour later, etc. At the same time it's good to apply abundant water to the root area.
I've hosed down plants in severe heat numerous times and never identified harm from doing so. Water evaporating from leaves will cool the leaves.
If your plants haven't been watered for a while, water them. I normally water my trees once a month, and it's time. But I just checked them and nobody appears to be in trouble! But some trees suffer damage without showing it. Their fruits become inedible: feijoa, jujube.