Crimson was trying to follow up saying the nonlethal damage dealt to you via weather was in fact [Cold] based since it was from a cold source. Makes a lot of sense really. It just falls short of how the rules handle it.
That's actually exactly backwards from my line of reasoning. From the way Frostburn describes Unearthly Cold environments, cold resistance reduces (or, in sufficient amounts, eliminates) the damage from a cold environment. Since reducing cold damage is all and exactly what cold resistance does, that implies the damage is cold-typed.
Since you brought up Sandstorm, notice that fire resistance offers no protection factor against hot environments (below Burning, a.k.a. Fire Dominant) and, since nothing says otherwise, does precisely jack squat against the damage hot environments cause. This implies that such damage is
not fire damage and, since it's not explicitly described and nothing explicitly reduces it, we can infer that it is untyped (although it should be tracked separately from other damage, since it can't be healed until the character reaches a milder environment or achieves a stronger protection level).
