Awpangle, it's different every time you go, hard to predict anything. The only other thing about July and August that seems to make a difference, is that school is out of session, and many local kids and teens and young people who are not into naturism come down to the springs, in my experience, more than in other times of the year.
I've been there on summer Fridays and had the whole entire hot springs to myself, the only person there. (For a little while.) I've been there and had partiers and bros take over. I've been there with 30 skinny-dippers, none of whom came in a big group, all just joining in the freedom of the springs. In general, in my experience, Friday can be a good day, but also when the weekend partiers start to arrive later in the day. Tuesday Wednesday and Thursday are midweek days I try to hit usually, instead.
That said, I had a friend head down to the springs on Thursday. He said it was a completely gorgeous day, but aside from two women enjoying their top freedom, there was just one male skinny-dipper, whom he described as "that guy who has long hair and a sarong," and looked to him like some baseball player, which made me chuckle as that is of course Hippie Dave. Holding down the fort...