10 Best Thermal Base Layers 2025 in the United States

The Under Armour Men's HeatGear Armour Leggings are designed for those seeking a high-performance thermal base layer. A standout feature is the super-light HeatGear fabric, which offers excellent coverage while remaining lightweight, making it ideal for activities where mobility is key. The strategic mesh panels enhance ventilation, ensuring you stay cool and comfortable during intense workouts. Additionally, the moisture-wicking material dries quickly, effectively managing sweat. This can be particularly beneficial for athletes or individuals engaged in outdoor activities.

In terms of fit, these leggings provide an ultra-tight, second-skin feel that many users appreciate for its compression benefits, helping to support muscles during physical exertion. The ergonomic design with seams placed away from high-abrasion areas enhances durability, which is a positive for those looking for long-lasting wear. The addition of a drop-in strength pocket is handy for storing small essentials, showcasing the practical side of these leggings.

The Thermajohn Long Johns Thermal Underwear is a solid choice for anyone needing a warm and comfortable base layer during cold weather. One of its standout features is the ultra-soft fleece lining, which ensures that you stay cozy throughout the day. The material is a blend of 92% polyester and 8% spandex, offering good heat retention while also being gentle against the skin. This makes it a great option for layering, whether you’re out in the cold or just lounging at home.

Another strong point is the moisture-wicking capability. The breathable fabric helps to keep you dry by effectively removing sweat, which can be crucial during outdoor activities or even just running errands. Additionally, the 4-way stretch feature provides excellent mobility without causing discomfort or chafing, making it easy to wear all day long.

While the thermal underwear is designed for warmth, some may find it a bit bulkier than other options, which could affect how well it fits under tighter clothing. Also, being primarily made of synthetic materials, it may not appeal to those looking for more natural fibers, especially if sensitivity to synthetic fabrics is a concern. The product's care instructions recommend machine washing, which adds a layer of convenience, but may not suit everyone’s washing preferences. Despite these minor issues, the Thermajohn Long Johns serve well for anyone in need of reliable thermal wear, especially during cold seasons.

The Cuddl Duds AMAZON WMS TP - L/S Hunter Green thermal base layer is designed to keep you warm and comfortable in cold weather. Made from 93% polyester and 7% spandex, this set offers a good combination of durability and stretch, ensuring a snug fit and freedom of movement. The brushed fleece inside adds extra warmth, while the matte soft outside provides a sleek look. Weighing around 14.89 ounces, the set is relatively lightweight, making it easy to wear as a base layer or on its own.

One standout feature is its moisture-wicking fabric, which helps absorb and evaporate sweat, keeping you dry throughout the day. Additionally, the set provides 50+ UV protection, making it suitable for outdoor activities. The top includes thumbhole sleeves for added convenience and the leggings have a modern rise, both contributing to comfort. The tag-free label also ensures you won't experience any irritation.

On the downside, some users may find the heavyweight fabric a bit too warm for milder weather, and the set might not be the best fit for those looking for a more relaxed, loose-fitting option. However, for those needing a reliable thermal base layer that combines warmth, comfort, and a sleek design, this Cuddl Duds set is a solid choice.