Red Squirrel from Timmins ON got us beat. I'm further west but still in Northern Ontario, and last night's low was -37 C (that's about 35 Below F) here. Unfortunately, that's about "normal" around here for this time. In this small city, the coldest part of the year is mid-Jan to mid-Feb, and it is common to reach -30C overnight on several nights in that period. -35 to -40 C is always a possibility. I'm in my 70's now and can remember only a very few times (less than 5) in those years when I experienced temperatures below -40C. On the other hand, summer max's above 40C ( about 104F) are uncommon here, so summers never get really bad.
Regarding automobile anti-freeze, yeah, it needs attention when you live like this. I'm a chenist so I understand how they work. Pure auto antifreeze (based on ethylene glycol) does NOT have an adequate freezing point. MIXING that with water at the right proportions is how it's done. It turns out that the optimum is about 60% antifreeze and 40% water, to get a freezing point between -50 to -60C. There is some variation because commercial products have other copmponents besides the ethylene glycol, so you need to follow the maker's instructions. It can be a bit tricky checking it, though - the simple testers you can get for density of the fluid are not completely accurate. There's also a source of confusion becasue you can buy a pre-mixed antifreeze that already has a glycol / water mix that you do NOT dilute, and you need to be sure what freezing point it has. When using that stuff you can only "top up" with it if you are sure what is in there already is strong enough before adding more. Antifreeze really SHOULD be used in all cars, not just ones in the cold places. Besides giving you freezing protection, they also give you a higher boiling point for hot places, and include corrosion inhibitors to prolong engine life.