Based on reading what @olavrb posted, it looks like the supported operating temperature range is from 32°F to 95°F. They do get warm on their own, though, so I suspect it would actually work at lower temperatures than that, though if it were powered off and allowed to cool to a lower ambient temperature, it might not work right again until warmed up (and it might or might not do that on its own).
However, I'm more worried about high temperatures in the summer. A maximum ambient temperature of 95°F is likely to be exceeded in an unventilated outdoor building during the summer in Wisconsin, and the device may be more prone to issues from overheating than getting too cold.
