An outer layer is the protective part of your layering system—the piece that faces wind, rain, snow, and abrasion. For changeable hiking weather, carry a waterproof or wind-resistant shell even if the day starts clear. A lightweight windbreaker suits dry, breezy conditions, while a waterproof hardshell is the better choice for sustained rain, exposed terrain, or mountain storms.

Start with the weather and your activity level. Look at waterproof protection for rain, breathability and ventilation for active climbs, wind resistance for exposed routes, and weight or packability if the layer will spend time in your backpack. A softshell offers stretch and breathability in mostly dry conditions; a hardshell prioritizes dependable weather protection.

Both constructions combine a face fabric with a waterproof membrane. A 2-layer shell usually uses a separate lining and often feels comfortable for everyday wear. A 3-layer shell bonds the face fabric, membrane, and protective backer together, creating a durable, streamlined construction well suited to frequent hiking and demanding weather. Also compare waterproof rating, breathability, seam sealing, hood design, and ventilation.