The best I could get easily ( and Trixxy ) in the UK was gutter sealant which seems, from my investigations to remain flexible down to -30C over a week. I do not know how long term it will work but am fairly confident it will be ok

However, after some looking around I saw this

-71C to 350C .. nice big range.

Trixxy, you may wish to try this if you have not started yet, seems ideal.

This is UK of course, but assume similar where you live. -71C is -96F if i got my conversion right