First suggestion. Find another hotel.
That place has nice rooms but that's it. And the rooms are truly only average. The pool is puddle in the middle of cement and a hundred or so chairs. At least there won't be too many people there.

I was just there last weekend. The temp was perfect, in fact a little cool for this time of year. I think it maybe hit 105 one day. But the humidity was in the high 80% range. Felt more like Florida than California.

As far as things to do. Depends on what you're into. On a recent trip the GF and I took the tram up then hiked to the top of the mountain and back
Takes all day and it a hell of an uphill walk but well worth the effort if you're into that kind of stuff.