temperature is not the problem
condensation is

I keep my mics in bags and cases
with a de-moisturizer patch (not sure about the name)
when this thing colours reddish, it can no longer absorb moisture

cheers

Cold breads moisture, and mositure + power = product failure.

All gear is designed to be used within their spec'd temperature range. If you are using gear outside that range, it won't likely meet it's perfomance spec's. In the ideal world, temp should be within the operating range of the gear and be stable for at least few hours before it is used. About 50-degrees inside temp would be the lowest I'd ever power on anything I cared about.

Insulate your gear with a thick blanket, sleeping bag, ect... to help protect it.

Curiosity, what about while not in use? Is it dangerous to have a microphone in, say 20 degrees F weather overnight or something of the sort?

Because I run a substantially large Remote Truck, my equipment is exposed to extreme temperature fluctuations between summer & Winter. It's not always powered up 24 hours per day. In fact is only powered up when I'm working. While heat is the great destroyer of equipment, cold equipment that is not up to temperature will frequently not perform in an ideal manner. Yes, it is actually a fallacy that transistorized/IC chip silicon devices don't need to warm up. They absolutely need to warm up. In fact, having been a factory authorized service technician for MCI, Ampex, 3M & Scully, I actually discovered that these machines need to warm up for more than 3 hours, even while at room temperature, before any alignment functions can be reliably performed. So even though we want our equipment to "run cool", we don't like it on the rocks, shaken or stirred. So I never tweak 24 track analog recorders until they have warmed up for at least three hours.

True, externally polarized, 48 volt condenser microphones can be affected by the cold, even more severely. Steamy breath can actually short out the microphone capsule causing, lowered output level & uneven response. While not all equipment indicates external operating temperature parameters, it's generally assumed that the equipment, in a professional environment, will generally be operated at normal room temperatures. Fahrenheit or, Celsius/Centigrade, your choice.

Nobody wants to listen to Golden Coldies
Ms. Remy Ann David

Very informative Remy.

I think this could actually be the causation of an issue I had in a post about Bluebird mic issues.

I work in a church, and the owner is rather gracious - but there is an issue w/ temp control vs/ outside, and it can get COLD in there at times