Yeah. Ice. The rivers, and whatever water ponds around, freeze to about 2’ thick in the winter. Yet, I won’t even let my dog on the river ice until at least mid December because currents and other factors affect how thick the ice becomes, and how fast. As I said above, for me, this is routine, but for folks who don’t know cold, it is a dangerous thing. The fact that ice if forming means the water temp is basically freezing - if you don’t drown, hypothermia will finish you off.
EDIT- “around here”. Depending on the fall, ice formation starts in November. And to echo @pmeisenheimer, a lot of folks up here who should know, don’t. Trucks went through through the ice on Lake Winnipeg this winter - ice fishers. And some snowmobilers like to play ‘puddle jumping’ in the spring. Racing across open water on a snowmobile. I like to think of Darwin, but most of these people have already had children.