Your training and natural hardiness have improved your natural resistance to cold temperatures.
Prerequisites: Base Fortitude save bonus +6, Cold Endurance.
Benefit: You gain resistance to cold 5. If you already have resistance to cold, it increases by 5 (maximum resistance to cold 15).
Special: You can gain this feat multiple times; its effects stack. You cannot have more than resistance to cold 15 as a result of taking this feat.
Source: Frostburn, page 48.