Worms in a ball can mean they are under stress. If there is no bad smell from the bin, it is unlikely that they have started to die, but they are trying to increase the chance of survival. You don't say what type of worm you have, but the temperatures you are describing would be on the hot side for E fetida (tiger worm) or E hortensis (euro night crawler/ dendrobaena.)
What size bin do you have- the larger the size, the easier it is for worms to find an area they are comfortable in.
Some members on this forum have put frozen bottles of water into the centre of their bins to cool them down. Not something I've had to do myself!
If you lack water, your bedding will not feel damp to touch.
No matter what it won't harm to put some fresh, wet bedding at the top of your bin and hold off feeding until your worms are behaving normally again.

There is something in the bin they are trying to avoid. It is nearly impossible to tell what that is over the internet,

What have you been putting in?

What is the bin made out of?

If there's no bad odor and the bin has drainage, I'd guess it's the heat. Can you bring the bin indoors? If not, the ice bottle is probably a good idea. I heard of a guy with a fish pond that would use an aquarium pump to run water through a coil of copper pipes imbedded in the bin. I get the feeling the bin and above ground pond were in a really hot shed. The pump broke when he was away for the weekend and he came back to find 99% had died. In other words, it really worked well! (When it was working.)

I agree. Sounds like you need to cool it down. Make sure it is NOT in the sun and bring inside if you can. What kind of bin do you have. That would help a lot if we knew.
Beth

Got pictures?
If not how big is the bin? Have you tried the ice bottles? How much of what are you feeding?

I wonder if you are seeing mites? Mites seem to send them into balls. I have found heat sends the worms upward, but I live in the north where upward is cooler.

Here is a link that might be useful: how to deal with mites in your worm bin.