Welcome to our forum.
 Tubbing in freezing temps....are you guys on crack??? So.....how low will you go??  How cold does it have to be before you will say, "NO" I won't go, it's too friggin cold outside to soak? You guys make me look like a girly-girl pansy!  I think my coldest soak was 29 degrees outside.  And then, I wore a goofy looking ski mask!
Same with me. Â Zero gets a little cold. Â Above 10 gets good. Â Wind is more an issue than temps.