outdoor cats in winte

Mi> What is the lowest temperature that is considered safe for cats?

I don't know for sure, but I had an old cat once (she was about 15 at the time) and I would generally not let her inside at night because she did not know how to use a litterbox and she was beginning not to wait to get outside before making a 'deposit'. I relented during a spell of pretty cold weather, but one night when it went down to 4 degrees above zero (REALLY unusual for here - Eugene, Oregon) I could not find her to let her in. She came back in the next day as if nothing untoward had happened. If you live in a residential neighborhood, I suspect that there are a few places that are warmer than others and the cats find them. For a while my older kitty was snuggling up with the neighbor's horses, but after they moved, I think she must have found another spot under a house or something.

... Cats: Proof that eating and sleeping aren't so bad.

The moms of all my ex-feral kittens have lived outside all their lives. I know it got below 0 last winter and they were still active enough to get pregnant with the kittens I now have. These girls are at a small Navy installation, so it's not residential but there are heated buildings with crawl spaces underneath. We never even saw them until they decided that they wanted some food assistance while they were pregnant. We've been feeding them ever since.