I can't imagine wearing knickers at 45 degrees! Or saving tights for below freezing. Of course, I used to wear mid weight wool jerseys at 65, but now I can wear short sleeved regular jerseys.
I also wear unpadded tights over my regular shorts, with wool socks ( I have 3 different thicknesses/lengths). This way, I can wear the tights for hiking or even x country skiing on a warmer day. I occasionally wear my wool/windproof Ibex tights that I bought for skiing, for riding. If it's that cold, it's usually just an errand or casual cruise on the hybrid. I don't regularly ride once the snow falls.
I bought a pair of padded Gore tights from someone on TE. I know she is as petite as me, but I cannot stand the chamois. It feels like a diaper. It's like spilling over the sides of the crease of my legs/body. I wear them because I feel guilty about spending the $ on something I really didn't need.
Your weather sounds like ours... one year hardly anything, next year blizzards galore.