10 Best Thermal Underwear Sets 2026 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 Set is a strong choice for anyone looking for quality thermal underwear that works well in various weather conditions. Made from 100% superfine 17.5 micron merino wool, this set offers excellent softness and comfort without the itchiness often associated with wool. The midweight fabric (250 g/m²) strikes a good balance—not too bulky but warm enough for cold conditions. Fit is described as comfortable for daily wear, designed to avoid bunching or overheating.

One of the standout features is its natural moisture-wicking ability, which helps keep sweat away from your skin, making it feel dry and fresh during activity. Alongside that, the fabric resists odors naturally, so you can wear it longer without worrying about smell. The set includes both top and bottom pieces plus a merino wool beanie, adding good value and versatility for outdoor use or layering.

Care-wise, the recommendation to hand wash and lay flat to dry might be less convenient for some, though the fabric is durable if cared for properly. Machine washing is noted as possible, but the gentler method will help maintain longevity. Since the product is imported and specialized, it may carry a higher price point, but the brand backs its quality with a satisfaction promise. This thermal underwear set suits men seeking comfortable, breathable, and naturally temperature-regulating base layers for winter sports, outdoor work, or everyday cold weather wear. If you want something soft, odor-resistant, and effective at moisture management, this set delivers well. However, if you prefer easy machine washing and don’t want to handle delicate care, you might want to consider alternatives.