The manufacturer chooses the desired environment enveloppe., and designs the aircraft for those paprameters, mainly temperature effects. As Underfire states, if the u/g cannot cope as a design for the chosen low temparatures, then the certified minimum temp for raising the gear becomes the left border of the enveloppe and that could be substntial warmer than siberian temperatures. In that case, the aircraft will have a limitation in the AFM for not operating in Siberia, so to speak.