Well for some of us the weather is quickly starting to drop and in no time the ugly white stuff will be dropping from the sky. Right now in my region (Massachusetts) we are getting weeks with highs in the 50's and lower lately. I'm not much of an outdoor rider once snow flies anymore because of my asthma and cold temps so indoor training rides with some treadmill work start once the white stuff falls. I might manage a couple rides outside in January and February if a little window opens for it.
So where is your outdoor riding limit, or do you still ride outdoor all year long no matter the temps and conditions.

Good bikes mostly stay home once salt is on the road. Road bike sometimes comes out and gets a very thorough wash afterwards - so slightly negative C's are okay. In-town commuting (<10km per trip) continues year round, which usually means down to -20C. Covering your mouth helps keeping the air you breath a bit warmer.

apparently I don't have one. but the cold takes it's toll in so many ways. I dial back performance expectations & strive for time in the saddle as opposed to miles, max speed & higher avrg speeds. if the roads are terrible & dangerous that's more of a factor for road riding. last year I explored lots of hard surfaced off road trails & that was really fun. was able to easily get 2 - 4 hrs of outdoor exercise w ea trip