According to the technical specs you are safe if you allow the unit to warm up to 10° C before switching it on - except if you cycle across the Mount Everest:
Operating temperature: 10° to 35° C (50° to 95° F)
Non-operating temperature: −20° to 47° C (−4° to 116° F)
Relative humidity: 5% to 95% non-condensing
Maximum altitude: 3000 m (10,000 feet)
Get some reusable gel hand warmers. Doesn't cost a fortune and should do the job just fine.
Sorry, I just found a link on Amazon Germany but you'll get the idea:
You can recharge them by putting them into hot water until the gel is fully liquid again. Then you just pop the small metal plate and they start to get warm. If you get e.g. 6 pieces, you can use 3 of them for the way to the practice room and the 3 others for the way back.
Reminds me of a gig I did at 3600m altitude. The Kemper was perfectly fine - the only problem was some band members getting altitude sickness! Good times!
¨ Environmental Requirements
Maximum altitude: 3000 m (10,000 feet)
Everybody with a Kemper is Cool.
Some of us are even cold blooded.
