Thermal shirts are designed to help you retain heat in cold temperatures. Made from blends of cotton, nylon, spandex, polyester, wool or fleece, thermal shirts are often used by skiers, hunters, hikers and others participating in cold-weather outdoor activities.

The waffle-wave pattern common on most thermal clothing is designed to trap in body heat, helping you to stay warm. Thermal shirts also tend to have cuffs that stay tight to the wrist to prevent body heat loss. The Centers for Disease Control and Prevention recommends tight-fitting cuffs at the wrists as an essential attribute of clothing designed for cold weather.

Thermal shirts are often worn under other clothing, though they can also be worn as a solitary garment. Most are long sleeved with a crew-neck collar. Though originally designed for men, thermal clothing is also available in styles for women.

Most thermal clothes can be machine washed. Read instructions regarding water temperature and whether or not to place thermal clothes in the dryer. Some blends that contain wool should be air dried to prevent shrinking.