Odin, the User's Guide says, "Operating temperature: 41°F to 95°F (5°C to 35°C)."
https://s3-us-west-2.amazonaws.com/c...de+-+en_US.pdf
I would not leave my Kindle out in below freezing weather. When I lived in Colorado I carried electronic gear next to my body if I had to be out in very cold weather. I was as concerned about condensation as anything else.