10 Best Thermal Underwear Sets 2025 in the United States

The Cuddl Duds Thermal Underwear set is designed to keep you warm and comfortable in cold weather, thanks to its cozy fleece lining and heavyweight feel. Made from 93% polyester and 7% spandex, it offers a good stretch that moves with you, making it comfortable for active wear or lounging. The moisture-wicking fabric helps keep sweat away from your skin, which is great for staying dry and warm during physical activities. Plus, it offers built-in UV protection with a rating of 50+, which is a nice bonus if you plan to wear it outdoors. The fit is modern and close to the body without being bulky, featuring details like thumbholes in the sleeves and a higher rise in the leggings for added comfort and coverage.

The product is machine washable and lightweight at about 15 ounces. Durability is generally solid given the dense knit fabric, but as with many polyester blends, it may pill over time with heavy use. This set is well suited for women looking for a warm, stretchy base layer that can double as casual wear in cold seasons.

The Cuddl Duds Women's Thermal Underwear set is designed for cold weather with a heavyweight fabric that includes a soft, brushed fleece inside for warmth and a smooth outside for comfort. Made from mostly polyester with some spandex, it offers good stretch, making it comfortable for active wear. The moisture-wicking feature helps keep you dry by pulling sweat away from your body, which is great for staying comfortable during physical activities or long days outside. It also provides strong UV protection, a nice bonus for outdoor use.

This set fits well with a modern rise in the leggings and thumbhole sleeves in the top, adding to the cozy, close-to-skin feel without bulk. The fabric blend should hold up well over time, and the tag-free label adds extra comfort. While it keeps you warm and dry, the synthetic material may not be as breathable as natural fibers for some people.

This set is a reliable, warm base layer that’s stretchy and comfortable for winter days, whether for layering or wearing on its own at home.

The Merino.tech Merino Wool Base Layer Men’s Set is made from 100% superfine 17.5 micron merino wool, a top-quality material known for being soft and comfortable without causing itchiness. This set comes in different weights, with the midweight version at 250 g/m² offering a good balance of warmth without overheating, making it suitable for cooler conditions or active outdoor use. It includes both a top and long john bottoms, plus a bonus pair of merino wool hiking socks, which adds value.

The natural moisture-wicking ability of merino wool helps keep you dry by pulling sweat away from your skin, and its odor-resistant properties allow for extended wear without developing smells. The fit is designed for comfort with no rubbing or bunching, important for base layers worn close to the skin. Additionally, the fabric breathes well, aiding in body temperature regulation so it can be worn across different seasons.

This set requires gentle care—hand washing and air drying are recommended to maintain durability and shape, which might be less convenient than machine washing. Imported and offered with a gift-quality presentation, the Merino.tech set provides quality and performance, making it a solid choice for men needing reliable thermal underwear for hiking, winter sports, or everyday cold weather comfort.