Heat Endurance( Sandstorm, p. 50)
Either as a result of growing up in the waste, or by training your body and mind to ignore the effects of searing heat, you can exist with ease in high-temperature environments.
Base Fortitude save +2,
Improved Heat Endurance (Sa) ,
You gain a +2 bonus on saving throws against fire effects. You can exist comfortably in temperatures up to 120° F without having to make Fortitude saves (see Heat Dangers, page 12). Your protection against heat is level 1 (see Protection against Heat, page 14).