Your winters are based on the jet stream dipping and causing artic air freeze you up. We do not ever get that. Its always above us. Our winters are normally warm when yours are cold and visa versa. Relatively speaking.
We actually have warm winters on a very normal basis. We can winters that rarely freeze. Or winters that freeze a lot.
So far, this winter is average. We have had around fifteen freezing nights, with the lowest being high teens.
I remember a winter back in the ice age, where it only froze one night in the whole winter. Then again, 20 or so years ago it every weekend in Jan. It normally snows here once every four or five years. It almost snowed this year. hahahahahahahahaha
So what your experiencing has no effect on us.
What effects my work is rain. Good winter rains means I get to see alot. The reason is ground cover, Snakes and gilas, need this to keep hydraded and keep the surface temps down. For instance, surface temps where the snakes winter on dry years can reach the 170's F. On wet years, they have the option of moist ground that cools the ground when it evaporates. Also, they can shelter in plant cover where I can still find them. On dry years, they do all their doing underground.
Back to temps. We can get seventy or eighty or even low ninties, anytime all year. Snakes do not care. We also find snakes active year a round, all the time, again, no change there.
Breeding is prey dependant and may be more influenced by monsoons here then anything else. Most reptiles here time birthing and hatching to occur after the start of the monsoons. Cheers