If you are doing extract like you said in the last sentence, you should have no problem keeping the boil if you have a decent burner. I have done so in temp in the 30s here in NM no problem (ya it does get cold here some times). But you also said you do all grain. The hard part for me is keeping mash temp. If you use a cooler pail, preheat it with hot water, then put the mash pail in the house to keep warm. Me I do biab mash in the kettle, and when it is real cold I have to keep hitting a bit of heat and stirring every 10 or 15 mins, so I haven't mastered perfect temp control yet, but it still comes out ok. I just made an insulation cover out of a fiberglass welding blanket ($20 at harbor freight), but haven't had the chance to use it yet.
I like brewing in winter, chilling the wort is a breeze.