The best fabric for extreme heat? It’s more complicated than you think

Choosing the right fabric for extreme heat is more complicated than most people assume. While the general advice is to wear light, loose, and summer-appropriate clothing, textile researchers reveal that fabric selection, weight, construction, fit, and color all play a significant role in how well clothing helps keep us cool. To maintain its cooling effectiveness, clothing must not hinder sweat evaporation, which is the body's natural response to heat.

Clothing experts suggest lightweight, open-weave, and loose-knit fabrics to maximize airflow and allow sweat to evaporate efficiently. Experts emphasize the importance of fabric weave or knit structure over the fiber type itself. Cellulosic fibers like cotton and flax (linen) are generally more breathable and comfortable compared to synthetic fibers.

However, the weave or knit structure of the fabric plays a more critical role than the fiber content in determining breathability. Wicking fabrics are designed to move sweat away from the skin and spread it over a larger area, which can help it evaporate faster. Synthetic fibers are commonly used in sportswear for their wicking properties, but wicking and cooling are not the same thing.

Wicking can make clothing feel drier, but evaporating sweat closer to the skin provides more direct cooling. Fit also matters. Clothing should allow for ventilation to facilitate airflow and help sweat evaporate more effectively. The right fit depends on the activity being performed. For example, a tighter-fitting synthetic tank top might be preferred for outdoor exercise, while a looser cotton T-shirt may be more comfortable for sitting on a porch or doing light yard work.

Cotton and polyester are the two most common fabrics used in clothing. Cotton absorbs sweat but can become heavy when saturated, while polyester moves moisture across the fabric and dries quicker. Polyester is widely used because it is inexpensive, durable, and versatile, but it may become uncomfortable in hot weather as sweat accumulates against the skin.

However, polyester can be engineered to move sweat across the fabric and help it evaporate. In extreme heat, deliberately wetting clothing can provide evaporative cooling, especially for older adults who may not sweat as effectively.