I looked at a few websites and they all said that dogs with heavy coats are more likely to get it and keeping them well brushed and clean will help. Perhaps her thick undercoat from winter is trapping moisture and causing problems? Maybe a regular grooming schedule would help? Is she on flea and tick preventative? It sounds like flea and tick bites can cause it too. I've never had a dog with hot spots but I've seen a few and they look painful, I hope Star is feeling better soon. Here's a couple of links about hot spots.

http://www.thepetcenter.com/exa/hotspots.html
http://www.canismajor.com/dog/hotspots.html