I was there in February a few years ago. There wasn't any snow on the ground but it was damn cold. We camped at White Pocket and the night temps were in the low teens. The temperature during the day was cold but not unbearable. We saw only 3 other people during our entire time at the Wave and we were there all day, leaving after sunset.
Good luck with the permit and enjoy the trip!
Thanks. I'd assumed you meant Fahrenheit and I've no intention whatever of camping (too sybaritic). What are the skies likely to be like?
I'll put in an application for a ticket and see how it goes, I think.