All of us have a "threshold" for riding. I suggest you expand yours at least down to the freezing point. Lots of good riding to be had all year long, as long as the roads are dry.

You can ride what you have. Just wear the appropriate gear. I ride my road bike with conti GP4000s tires all year long.

Your PR2 tires may be a bit "sticky" and attract the road grit they spread out for icy weather, so you may wish to get a set of krylion or gatorskins for the cold.