Dry or humid environment has no bearing on cold hitting hot and can produce moisture. Example HVAC closet supply leak at duct board I have discovered mold lab tested. The closet is indoors or in envelope of home indoor humidty at around 50% so why did mold grow on drywall?

So I still believe mold can and will grow in a Las Vegas attic under certain conditions.

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Chip
Destin,Fl
"The only non-addressable objection is the unkown"