Not sure if the adhesives used for the surrounds and coils can withstand sustained low temperatures.

Then there's the ferrofluid for the tweeters. Depending on the compound, it may expand and there may not be enough room to accommodate the expansion.

Axiom has an environmental chamber but I'm not sure if they've characterized long term, low temp performance.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated