Mostly it seems to be in the mindset of the shooter. I've gone out when it was cold enough that I preloaded magazines so as to not risk sticking a bare finger on metal magazines.
Some of which also comes down to the quality of your "snivel gear" too. If your winter gloves let you feed rounds into magazines, and also keep your fingers warm, then you are ahead of the curve. (Or, if you have invested in stripper clips to take a bunch of the "fumble" out of magazine loading.) But, it's the little things, like boots that keep your feet dry. Or not relying on cotton socks. Having use-able rain gear and some way to keep range bags and cardboard ammo boxes dry.
(Most of the ranges here in Texas will shoo you off if it's a thunderstorm, as lightning hits on the customers seems to not be a covered liability.)
At the other end of the spectrum. Hydration is key. Both before and after the trip out to the range. Choosing breathable clothing, good shade, shading clothing and the like are key, too. Like not wearing shorts and open-toe shoes when you know you are going to be in a prone shooting situation (unless you have a superb shooting mat).
And, being in a hot humid climate, weapon care versus salt sweat can be more of a task than coping with sleet or snow or rain. (And each of those deserves the special attention they need, too.)
For me, around here, the limits are going to be around a Heat Index of 100º and then down to around a Wind Chill of 20-30º. But, those are both extreme sorts of climate conditions, here, too. If the "jerk quotient" at the range is low enough, I can better tolerate HI of 90º+; if we've not had an "ice event" then I can go out in colder conditions, too; if the jerks stay home.