Best observing sites will be just about anywhere. The weather will be 40s high most of the time and 20s lows most of the time, but the lows could be very low (in the negatives F) and the wind may be terrible at any time (or most any time). Precip won't usually be much (still in the rain shadow) but may be snow if it comes and will almost certainly be snow if at night.
I think those are the worst two months at this location - I'd go somewhere else if possible.
Hmmm... good to know.
Seeing as that's the darkest area within a day's drive, I'd still kinda like to use it if possible. Would going in early December make any difference? I'm pretty flexible time-wise.
The goal is to catch the remaining Herschel objects of winter; I've got stuff in Auriga, Gemini, Canis Major, and Puppis to observe, and the weather here in western Oregon is usually crap Dec-March. I suppose I could find somewhere in SE Oregon, but I'm not sure conditions there would be any better.