Understanding CLO Values
CLO is a unit of thermal resistance. One CLO is roughly the insulation needed to keep a resting person comfortable at 21°C in still air. Understanding your clothing's CLO value helps you plan for cold exposure:
- 0.3 CLO: Light summer clothing — minimal protection
- 0.7 CLO: Standard hiking outfit — base layer, fleece, shell jacket
- 1.0 CLO: Heavy winter layers — expedition-weight base, insulation, shell
- 1.5 CLO: Extreme cold gear — down suit or equivalent
💡 Wet ClothingWet clothing has roughly 1/5th the CLO value of dry clothing. Rain and wet snow can rapidly increase hypothermia risk even at above-freezing temperatures.