What do you consider “extreme” cold?

Quantum suicide is really interesting, I’ve always thought something like this could be possible and this is the first time I’m learning that there’s a word for it. There’s something intuitive about it, I bet lots of people also feel the same way. I’ve been in a few potentially near-death situations and one specific thought always pops into my head afterwards, “I wonder how many versions of me just died from that.”