10 Best Thermals 2025 in the United States

The Merino.tech Merino Wool Base Layer Mens Set stands out for anyone needing reliable thermal underwear. This midweight set, weighing 250 g/m², offers an excellent balance of warmth and breathability, making it suitable for various weather conditions. One of its major strengths is the use of 100% superfine merino wool, which provides a super soft feel and exceptional comfort without the itchiness associated with some wool products. This set is particularly appealing for outdoor enthusiasts as it features natural moisture-wicking and odor-resistant properties, helping wearers stay dry and fresh throughout the day.

A key advantage of this product is its layering compatibility; it fits comfortably under other clothing without causing bunching or overheating, which can be a common issue with heavier materials. Plus, its durability is enhanced by the recommendation for hand washing, though it can also be machine-washed, ensuring ease of maintenance.

However, there are a few drawbacks to consider. While the merino wool offers a lot of benefits, it may require more careful handling than synthetic materials. Users must adhere to the care instructions, as improper washing could affect the garment’s longevity. Additionally, since this product is specifically for men, it may not cater to a wider audience looking for unisex or women's options. Lastly, the inclusion of a pair of Merino Wool Hiking Socks adds value, making it an attractive gift option. However, potential buyers should be aware that the price point may be higher compared to synthetic alternatives. Those seeking warmth, comfort, and moisture management in their thermal wear will likely find this set to be a worthy investment.

The Cuddl Duds Thermal Underwear set for women is designed to keep you warm and comfortable in cold weather thanks to its brushed fleece lining inside and a smooth, soft outer layer. Made mainly from polyester with some spandex, it offers a good stretch that allows easy movement and a snug fit without feeling tight, which is great for active days or lounging. The fabric is heavyweight and densely knit, providing decent warmth without bulk, making it suitable as a base layer under other clothes or worn alone for casual wear.

One strong point is its moisture-wicking ability, helping to pull sweat away from the skin and keep you dry, which is essential for staying warm. Additionally, it offers protection against UV rays, a bonus if you spend time outdoors in the winter sun. The set includes a top with thumbholes and leggings with a modern rise, designed to stay in place and provide full coverage. It’s also tag-free, adding to comfort. Weighing around 15 ounces, it is light enough not to feel heavy but still substantial for cold weather.

While the polyester fabric is durable and easy to care for with machine washing, it may not be as breathable as natural fibers like wool, which some might prefer for long outdoor use. Also, the fit might vary, so checking sizing is important for the best layering experience. This set is suitable for those looking for a warm, stretchy, and moisture-managing thermal base layer that performs well in everyday cold conditions.

The WEERTI Thermal Underwear for Men Long Johns are designed to provide excellent insulation and comfort during cold weather. Made from 92% polyester and 8% spandex, the material is both lightweight and stretchy, allowing for a snug fit that minimizes heat loss without restricting movement. This makes it suitable for layering under various types of clothing, from casual outfits to formal wear. The fleece lining adds an extra layer of warmth, ensuring you stay cozy in chilly conditions.

One of the key strengths of this thermal underwear is its moisture-wicking capability. The fabric efficiently wicks away sweat, keeping you dry and preventing that clammy feeling often associated with other thermal wear. This feature enhances comfort, especially during active use or long periods of wear. In terms of durability, the strong seams and 4-way stretch fabric ensure that the thermal underwear can withstand regular use without tearing or losing its shape.

However, because it is imported, availability might be an issue, and it may take some time to receive if ordered online. The fit is described as snug, akin to a second skin, which might not be preferred by those who like looser clothing. Additionally, while the polyester-spandex blend is good for moisture-wicking and flexibility, it might not be as breathable as some natural fibers like merino wool. This thermal underwear set is ideal for men seeking a reliable base layer for cold weather that offers warmth, moisture management, and flexibility, making it a good choice for winter sports, outdoor activities, or even just staying warm indoors.