Disclaimer *my opinion from my experience*
Well, you'll always have fish in those coves. You'll always have fish deep. At all times of the year this is true.
The answer to your question will vary from lake to lake and you won't know, down to the specific degree, what the precise answer is without knowing that lake very well and having been monitoring the temps closely all season.
Bass do pretty well in low 80s all the way to low 50s. They don't mind spending some calories to chase bait in that entire range of temps. They will absolutely start to slow down mid-high 80s and low 50s to high 40s, but they will still bite.
If the lake I'm on every weekend has a highest temp in the hottest parts of the summer of 87 degrees, then I'm going to start moving shallower at around 77-72 degrees. If the highest temp is 92, I'll start moving shallower at 82-77 degrees. 10-15 degrees cooler than the hottest temps they've seen will be when their instincts start taking over and they'll start to truly realize "winter is coming" regardless if that's 82 degrees or 72 degrees. Bass up here in Minnesota don't hardly get to see 85+ water temps. Southern bass see that regularly.
So, long story short... If temps are below 75 (regardless of state), you're pretty safe to start using faster baits, topwaters, reaction baits, and move shallower. It does vary from state to state and lake to lake but that's a fairly safe number in the fall. It will just continue to get better and better the further below 75 it goes... All the way until about 55 you'll notice they're slowing down and then low 50s and higher 40s is when they're truly going to start going into winter pattern and moving down to escape the chilly surface temps.