I haven't been willing to try it. The tanning formula I use says 60-65 degrees minimum. Hopefully someone can answer, I'm curious because I have pelts that need to be done.
I might can answer myself in a couple days. We had a warm spell and I started a couple pelts. The overnight temps are now plummeting (for here) before I’ve finished them.
In what way? Generally, cold slows down processes. The only real advantage is that in super cold weather you can freeze dry hides and they soften easier. But that only works if it's really cold for awhile.
I know the rittles EZ kit used to say not to the the kit freeze. Might be others . If your bucket tanning just bring it into the house.. unless you have kids and you're using something like Krowtann(formic acid) or other rather nasty chemicals).
If you have some stretch in the leather you can sew the eyeholes and the bullet hole before blocking. When you take the stretch out of the leather when blocking the puckers from any repairs will disappear.