I draw the line at about 38 degrees, I don't like the rain and don't leave in the rain, but when I get caught, there is no choice. I have riden from Arkansas to Ohio in the rain 2 days straight, that gets old fast.
I've ridden during the winter, but I won't risk riding if there's a chance of ice on the road. We don't get along...
Just about anything above 40F, I'm game... unless it's raining when I start out.
I did ride from Durham to Charlotte last winter in a cold rain but only because it was going to be in the upper 60'sF the next morning in the mountains.
But then again, I don't like riding when it's in the upper 90'sF either.
The trick is you spend the summer in the Northern Hemisphere and the winter in the Southern Hemisphere..............Just ask Hombre about that.
Personally, I got the KLR for that sloppy weather. It takes too long to clean the Rock. The KLR is a pressure wash away.
I don't think I have the balls to ride the Rock on slippery, snow covered roads anyway. I can't imagine dropping an 800+ pound bike and picking it up alone or worse, having it on top of me, pressing me down on the cold, slushy, snow covered pavement.
I can think of lots of better things to do or places to be at.