For a while, I was living in Marquette, MI and that got to -10 to -20F (-23C to -29C) many days during the winter, even during the day, and that was before fact

For a while, I was living in Marquette, MI and that got to -10 to -20F (-23C to -29C) many days during the winter, even during the day, and that was before factoring in the wind chill and the 3 feet of snow around you. They'd frequently cancel classes because it was dangerous to go outside if you had any skin exposed. And Marquette is a relatively small town that I'd classify as mostly "walkable". But on those days, walking 2 miles to the grocery story was not something anyone should have been doing nor were the roads or sidewalks clear enough to ride any kind of bike (if you even can at those temperatures). I now live on the other extreme in Phoenix, AZ and during the summer, you'll see 115F (46C) or higher for ~2 months a year with no cloud cover. That's hot enough that you don't even really sweat while walking; it evaporates so quickly that it can't do its job. We've had people at my office go for walks during lunch and collapse after 15 minutes due to it. And Phoenix is one of the most unwalkable places to live imaginable from a layout/distance standpoint to boot. But I will admit both of those are in the extremes and most of the country isn't like that, although many areas will have quite a few days that go subzero (-17C) and over 100F (38C) each year. I think a big thing the US needs to do is start rezoning areas and rely less on everyone living on a half acre of land 2 miles from the nearest non-residential building. Unless that happens, much of the US won't be able to realistically implement policies like Paris is.