I haven’t seen this spec’d anywhere. What is the imp guaranteed operating temperature range? For any outdoor application or even for a garage door opener I would think it would need to be something less than 0 deg. C.
Except in California, of course.
The spec is for -20C -> +55C operating.
If you have the imp in an enclosed space and don’t enable power-save, it’ll dissipate ~250mW which will self-heat it quite well though 
Hugo, what about the storage temperature range?
We don’t spec storage; you’re likely fine in the -40C -> +85C range, but I’ve not looked at the specs of all the chips (eg: the processor is fine -65C -> 150C storage, but they don’t quote data retention of the flash for that range).