If it weren't for the ice and grit I wonder how cold it would have to be to stop me going out. I was forced once (because I was at Pooley Bridge and overnight everything had iced over) to ride to Sheffleld in conditions I wouldn't plan to go out in. Had to buy another pair of socks on the way. God it was cold!
I think my lowest temperature to set off riding (as in I leave my house to go for a ride for pure pleasure) is about 5C.
I'll go out at anything much above freezing, say 2°C provided its dry. Its not so much the temperature, you can dress for that, it's the risk of slippy stuff that stops me.
I go in anything except ice although in my teens many many years ago still didnt stop me, and no gloves or fancy warm gear in them days or taking it steady, just flat out everywhere. Mad really but hey ho, who gives a toss, i,m still here, just.🤪
And yes I've been caught out in snow on a bike and always hated every second of it. If the roads have been recently salted it was usually OK, fresh snow has a surprising amount of grip (almost as much as my arse on the saddle), compressed snow can be horrible but just about doable until it freezes. There is a reason for cars with all season tyres 🙂