10 Best Thermal Long Johns 2025 in the United States

The WEERTI Thermal Underwear for Men Long Johns is designed to be a reliable base layer for cold weather. Made from 92% polyester and 8% spandex, the material is lightweight yet offers warmth and comfort. The fleece lining helps in trapping body heat, making it suitable for layering under various types of clothing, from formal wear to casual outfits. The snug fit mimics a second skin, minimizing heat loss, while the 4-way stretch fabric ensures full mobility and flexibility without tearing the seams prematurely.

This is ideal for those who need comfortable yet durable thermal wear for both outdoor activities and lounging at home. The moisture-wicking feature is a significant advantage, keeping sweat at bay and maintaining dryness throughout the day, which is essential for staying comfortable in cold conditions. Additionally, the fabric's odor resistance helps in maintaining freshness after extended wear. However, a potential drawback is the polyester blend, which might not be as breathable as natural fibers like wool. Also, the fit being snug may not be suitable for everyone, particularly those who prefer a looser fit.

Nonetheless, these long johns offer a good balance of warmth, comfort, and functionality for cold weather use.

The Cuddl Duds Thermal Underwear set offers a cozy and practical option for women looking to stay warm in cold weather. Made from a polyester and spandex blend, it features a soft, brushed fleece interior that provides warmth without feeling bulky. The spandex content gives the top and leggings a comfortable stretch, making it easy to move around or layer under other clothing.

This set is designed to wick moisture away from your skin, helping to keep you dry during physical activity or throughout the day. It also offers added UV protection, which is a nice bonus if you spend time outdoors. The seamless design with a tag-free label and thumbholes in the sleeves adds to comfort by reducing irritation. Weighing just under 15 ounces, it’s lightweight enough to wear for extended periods without feeling heavy.

It is suitable as a base layer or worn on its own indoors, meeting the needs of anyone seeking warm, stretchy, moisture-managing thermal wear for everyday winter use.

These Merino Wool Base Layer pants are made from 100% superfine Merino wool, known for its softness and comfort without itchiness, making them great for all-day wear. The midweight fabric (250 g/m²) offers a good balance: warm enough for colder days but breathable enough to prevent overheating. Thanks to the natural moisture-wicking and odor-resistant properties of Merino wool, these long johns help keep you dry and fresh even during active use.

They are designed with a pull-on closure for easy wear and are machine washable, adding convenience. The fit is snug to serve as an effective base layer, with sizing options like X-Large ensuring a comfortable match. An added bonus is the included Merino wool socks, which complement the pants for a full base layer setup.

These pants are ideal if you want natural temperature regulation and odor control in your thermal underwear, especially for hiking or everyday cold weather use. If you prefer synthetic fabrics or require very heavyweight insulation, other options might be more suitable.