I'm in Ottawa too and our daughter will often nap in her stroller at temperatures of -10C or more while we're out for a walk. I probably wouldn't specifically

I'm in Ottawa too and our daughter will often nap in her stroller at temperatures of -10C or more while we're out for a walk. I probably wouldn't specifically stick her outside for a nap but in general the cold (or indeed sleeping in the cold) is no big deal for kids as long as they're dressed well.