The Best Thermals for Outdoors

Thermal underwear for outdoor recreation is designed to keep you dry and warm. Though the outer layer of a jacket or coat is you first line of defense against cold, wind and rain, thermal underwear is designed to hold body heat close to the skin. Another important consideration for thermals is their ability to wick sweat away from the skin. After long hours of physical activity or wearing a heavy coat, staying dry will quickly become a top priority.

  1. Cotton and Wool Thermals

    • Cotton is not a recommended thermal insulator for the outdoors. Once wet from snow or sweat, cotton thermals can actually make you colder. Wool thermals are designed to be soft on the skin while maintaining their natural thermal efficacy. Two other benefits of wool thermals are that it wicks away sweat, and the natural chemical structure of wool has antibacterial properties. Synthetic blends containing wool are also effective in wicking away moisture and insulating. However, wool takes a while to dry, which can be inconvenient if you will be spending more than one day outdoors.

    Synthetic Fabric Thermals

    • Synthetic material will maintain thermal properties even when damp. Polyester wicking thermals tend to be effective at insulating and wicking away moisture. However, polyester thermals can tend to over-saturate with sweat during prolonged periods of excess sweating. Polypropylene is an effective wicking and insulating fabric frequently used for thermals, and is reasonably priced. While polypropylene is a great insulating and wicking fabric, it does little to contain moisture. Wear polypropylene with an absorbent outer layer such as fleece.

    Top Brands and Fabrics

    • Wickers is a company which strictly specializes in thermal underwear, and was well reviewed by "Backpacker Magazine." Polartec makes several styles of effective synthetic underwear with particular focus on fit, wicking power and wool blends. Capilene by Patagonia is among the best selling fabrics for thermal underwear, and is offered by many stores including Williams Sonata, REI and Hudson Trail.

    Additional Top Brands and Fabrics

    • There are many brands to choose from, but some of the most widely purchased thermal underwear fabrics include CoolMax, Duofold, SmartWool and Thermotech. CoolMax fabric is offered by Spyke, Bike Tec and Quicksilver. Duofold thermal underwear fabric is sold by Champion and Campmor, among others. SmartWool is a natural and synthetic blend fabric offered by Back Country, REI and Campmor. Thermotech fabric is among the favorites of ski enthusiasts and offered by Sun and Ski, Ski Stop and Ski Chalet.