Neo,
I was there last Saturday. I arrived around 10:30 and left around 2:30. Not a drop of rain during my visit. It was clear when I arrived at Bowen, but was partly cloudy to overcast the rest of the day. Rain never threatened however. When I got back down the mountain to Devore, it was sprinkling.
When I arrived at 11:00 or so there were 8 to 10 people there, most with suits. As the day wore on more folks arrived, up to 30 or so? Most were suited, but some were topless or clothes free. It was a very social day, as it was cool and most everyone hung out in the hot springs.