15+ and I will stay home, though I had my best single afternoon of calling on a very high wind day.
I did 9 stands, and called in at least one coyote on each stand.
On windy days, I make my stands much closer, sometimes only 200yds apart, and spend about 10 minutes per stand.
My reasoning is they can't hear me from long range, so they should respond faster.
As others have said, get into the brush or ravines. Coyotes want to be comfortable while they snooze, but still smell and see danger, so you might find them higher on a hill, facing downwind, etc.