10 Best Thermal Underwear Set 2025 in the United States

The Merino.tech Merino Wool Base Layer Set is a midweight thermal underwear set designed for men. This set includes a top, bottom, and a bonus pair of merino wool hiking socks, making it a comprehensive package. Made from 100% superfine 17.5-micron merino wool, it promises exceptional comfort without the itchiness that can accompany wool fabrics.

The material is notable for its moisture-wicking and odor-resistant properties, ensuring you stay dry and fresh even during extended wear. The breathability of merino wool helps regulate body temperature, making this set suitable for year-round use. However, the care instructions recommend hand washing and air drying for longevity, which may be less convenient for some users.

The set is imported and weighs one pound, making it reasonably lightweight. The fit is designed to avoid bunching and overheating, which adds to its comfort during daily wear. While the durability is not explicitly mentioned, the promise from Merino.tech to ensure customer satisfaction suggests a commitment to quality. This set would be ideal for individuals looking for comfortable, moisture-wicking thermal underwear with added benefits like odor resistance and temperature regulation, though the maintenance requirements may be a drawback for those seeking easier care options.

The Cuddl Duds Thermal Underwear Set for Women is a solid choice for those looking to stay warm in cold weather. Made from 93% polyester and 7% spandex, the material is both comfortable and stretchy, ensuring a snug fit. The brushed fleece inside and matte soft outside offer a cozy feel, while the spandex stretch provides ease of movement. This set is designed to be heavyweight, which means it can handle very cold conditions well. Its moisture-wicking fabric helps keep you dry by absorbing and evaporating sweat, which is a big plus for active wearers.

The set includes thoughtful design elements like thumbhole sleeves, modern rise leggings, and a tag-free label, which add to the comfort and practicality. Its sleek design makes it versatile enough to wear as a base layer or on its own, making it suitable for both outdoor activities and lounging at home. The protection from harmful UV rays is an added bonus, especially for those spending time outside.

Durability appears to be strong with densely knit fabric, but like any clothing, it will need proper care to maintain its quality over time. Machine washing is convenient, and the set's design and material make it a durable option. This thermal underwear set is ideal for women who need reliable warmth and comfort in cold weather without sacrificing style or mobility.

The Merino.tech Merino Wool Base Layer Women Set is a versatile option for those seeking comfortable and functional thermal underwear. Made from 100% superfine Merino wool, this set is designed to provide a soft, itch-free experience, making it a great choice for daily wear. The midweight version at 250 g/m² offers a balanced level of warmth, suitable for various weather conditions. Additionally, the set includes Merino wool hiking socks, adding extra value to the package.

One of the standout features is the natural moisture-wicking and odor-resistant properties of Merino wool, which help keep you dry and fresh throughout the day. Breathability is another strong point, ensuring you stay comfortable without overheating. However, the recommended care instructions to wash on a delicate cycle and lay flat to dry may require extra effort compared to more low-maintenance fabrics. Durability is generally good, but like all natural fibers, Merino wool may require careful handling to avoid damage.

The set is also available in different weights (165 g/m² for lightweight and 320 g/m² for heavyweight), making it adaptable to various temperatures and activities. While the zero-worries guarantee is reassuring, the relatively high price point might be a consideration for some. Originating from China, the product might not appeal to those looking for locally made options.