Cold Homeland (3.5e Trait)
From D&D Wiki
Your were born and raised in frigid polar regions, and your body has become attuned to cold as a result.
Benefit: You gain a +4 bonus on Fortitude saves against environmental cold effects. Additionally, you gain cold resistance 1.
Drawback: You take a -4 penalty on Fortitude saves against environmental heat effects. Additionally, all Fire-based spells and attacks do 1 extra point of damage to you.
Special: This trait must be taken at 1st level if it is to be taken at all. You may not select this trait if you have permanent immunity to heat or fire for any reason. If you select this trait and later gain a permanent immunity to heat or fire, you lose the benefits of this trait.
Roleplaying Ideas: Your character is entirely comfortable in weather that makes everyone else shiver. On the other hand, you sweat in weather that everyone else finds pleasant. Your character background should mention where you were born and raised.