Yes, this is sun scald. It is made worse by fertilizing, especially fertilizing after flowering. Sun scald is especially common if shade trees have been pruned. Most rhododendrons adapt to their location. However, if the sun exposure is changed, this happens.

In your case, it is very easy to see the cause. In each case where there is severe sun scald, there is a stump where the stem was cut, maybe to cut off a flower. In any case, the pruning caused leaves to be exposed to the sun that were previously shaded by other leaves and they burned.

There is no biological reason to prune off the damage. If you don't like the looks of it, you can remove the damaged leaves, however this will cause the leaves underneath to get sun scald, just as these leaves got sun scald because the leaves above them were cut off.

This is one reason why it is very important, if you are going to prune, to prune immediately after blooming and even then expect some sun scald.

Those out-of-nowhere extreme temperatures like we experienced last week will sometimes cause the burning your plants are displaying....you might have avoided the damage if you had watered well the day before, or morning of, the record temps. If a similar forecast is presented again this season, keep that in mind - your rhododendron was transpiring faster than the roots could resupply leaves with water.

My own did fine, but a 15 yr old daphne odora looked like someone had torched it with a flame thrower on one side :(

It appears too from your photos that your rhododendrons are setting seed - if you will snap off those spent flower structures you can redirect energy being used in seed formation to next years flower bud set.

Thank you so much, rhodyman. And it makes perfect sense. The bush is planted right next to an over-grown and leggy forsythia. I pruned about a third to a half of the plant pretty far back, which probably took away some of the shade the rhody had. Talk about learning as you go. I'd gotten an ID on the forsythia and found advice about pruning ones that had been left too long as mine had. Now I'm seeing the results on its rhody neighbor. Yikes! Well, it seems pretty hardy and hopefully we'll go back to some overcast and cooler temps. And your advice about leaving the damaged leaves as shade for the ones under is VERY helpful. I'll leave them as they are.

morz8, your reply probably came in just as I was responding to rhodyman.
Thank you for the watering advice. I'll definitely do it next time.
As for snapping off the flower structures. I've looked at other posts about this. A neighbor just told us to pull off the wilted, dead flowers. But we should snap off all the other parts? They do "snap" so I think I know what you're saying. I was afraid I'd be defeating next year's flowering. Does anyone have a "before and after" photo for beginners like me?
Thanks again for the help. Clearly I need it!

Every year I mean to take a couple of deadheading photos, and then forget....

Just snap off the spent flower structure, leaving any new leaves intact on the plant

This one is Harold Greers....

Here is a link that might be useful: {{gwi:395570}}

Dead Heading:

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Locate the spongy layers at the base of the flower.

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Grasp flower just above spongy layer with 2 fingers and twist sideways to break off spent flower. Be careful not to disturb new growth which is fragile.

Perfect! Thank you so much.