I had several of the Lexar Pro CF cards fail. Not in cold weather just in normal working conditions. They were replaced under warranty. After the 4th or 5th, and no response from Lexar I quit using them. They started slowing down on write time, then scrambled file names. I have two left and only use them for test photos. I just don't trust them anymore. I switched them between 3 Nikons and had the same problem. I switched to SanDisk, same cameras with no problems. Batteries as others have said can fail in cold weather,especially if older. There are a lot of articles on the web covering cold batteries.