10 Best Women's Thermal Undergarments 2025 in the United States

The Cuddl Duds Thermal Underwear for Women is designed to keep you warm during cold weather with its brushed fleece interior and soft exterior. The material, a blend of 93% Polyester and 7% Spandex, offers good stretch and a snug fit, making it comfortable for active wear. The heavyweight fabric ensures warmth without adding bulk, allowing for versatile wear either as a base layer or standalone piece.

The moisture-wicking feature is beneficial for maintaining dryness, while the UV protection adds an extra layer of safety for outdoor activities. The inclusion of thumbholes in the sleeves and a modern rise in the leggings enhance the fit and comfort further. However, some users might find the fit too snug if they prefer a looser wear. The seam construction is designed to reduce chafing, enhancing comfort.

With machine washable care instructions, maintaining this thermal set is straightforward. This product is best suited for those looking for reliable, stylish thermal wear that can be used for both outdoor activities and lounging at home.

The WEERTI Thermal Underwear for Women is designed to keep you warm and comfortable in cold weather. Made from a blend of 92% soft polyester and 8% spandex with a fleece lining, it provides a good balance of warmth and flexibility. The material is lightweight, making it suitable for layering under other clothing without feeling bulky.

The snug fit helps in minimizing heat loss and provides a streamlined look, making it ideal for wearing under both casual and formal attire, or even as pajamas. The four-way stretch fabric ensures flexibility and freedom of movement, which is great for active users. The moisture-wicking feature is strong, effectively keeping you dry by transporting sweat away from the body.

This thermal underwear set is a solid choice for women seeking warmth, comfort, and flexibility in cold climates.

The 100% Merino Wool Women's Expedition Weight Bottoms are designed to provide superior warmth and comfort, making them ideal for outdoor activities in cold conditions. The material is a significant strength, as Merino wool is known for its softness, itch-free feel, and excellent thermal properties. The heavyweight 400 g/m2 construction ensures you stay warm, while the moisture-wicking properties help keep you dry by drawing sweat away from the skin.

Additionally, Merino wool's natural odor resistance means you won't need to wash these bottoms as frequently, saving water and time – a bonus for environmentally conscious users. The flatlock seam construction minimizes chafing, enhancing comfort during prolonged wear. The garment's weight is 12 oz for a medium size, providing substantial warmth without being overly bulky. These bottoms come in a wide range of sizes from XS to 3XL, ensuring a good fit for various body types.

Potential drawbacks include the imported nature of the product, which may be a concern for those preferring locally sourced items. Some may also find the price higher than synthetic alternatives, although the quality and benefits of Merino wool often justify the cost. The product is machine washable, which simplifies care, but users should still handle it with care to maintain its longevity. These thermal long johns are best suited for women who need reliable and comfortable insulation for outdoor activities in cold climates, especially those who value sustainable and high-quality materials.