Either because of growing up in a frostfell or training your body and mind to ignore the biting effect of cold, you can exist with ease in low-temperature environments.
Prerequisite: Base Fortitude save bonus +2.
Benefit: You can exist comfortably in conditions between 0° F and 90° F without having to make Fortitude saves (as described in Cold Dangers). You also gain a +2 bonus on saving throws against cold effects.
Cold Endurance doesn’t provide any level of resistance to cold damage.
Source: Frostburn, page 47.