The Worst Fabrics For Keeping You Cool In The Summer

Summer means wearing fewer and lighter clothes to combat the heat and humidity, but being smart about the clothes you choose — and the fabric they’re designed with — can go a long way to helping you stay cool.

While there are some obvious fabrics to avoid (tight leather pants plus sweat never ends well), others might surprise you, including one material that makes up the majority of our clothes. Choosing the right fabrics not only keeps you cool, it also keeps sweat and body odor at bay. Wearing the wrong fabrics can be uncomfortable at best, and encourage fungal growth at worst.

When picking out your clothes for the hot days ahead, take a second look at the tag to make sure it isn't designed with one of these worst offenders that prevent you from staying cool.

Polyester, nylon and acrylic fabrics are widespread in fashion, and you likely have something in your closet made from these. Around the turn of the century, polyester overtook cotton as the world's most produced fiber (a trend that's forecast to continue). But most polyester, nylon and acrylic fabrics are made from petroleum, essentially making them plastic.

Unless an item has been specially designed for athletic wear, synthetic fibers like polyester, nylon and acrylic are not great picks for summer. While a 100% polyester shirt (as compared to blends or performance wear) might absorb sweat, it still has an occlusive nature that retains body heat — and it tends to retain bad odors, too.

"Anything man-made is always going to struggle when the temperature soars unless it's had a specific treatment," explained Lily Rice, a freelance sportswear designer. Specially designed performance fabrics are a little different. The popular Nike Dri-Fit line, for example, uses a microfiber polyester, which makes all the difference. The strands are much, much smaller than your typical polyester and create an extremely lightweight garment, which allows it to better absorb moisture. Plus, the clothes have added antimicrobials to prevent odor, along with specially placed mesh panels that promote airflow.

But Rice says fabrics made from synthetic materials not designed for performance are the worst offenders for hot weather due to their lack of breathability and absorbance. Like plastic, these fabrics don't absorb moisture. Instead it sits on the surface, where it can eventually evaporate. "This means you’ll sweat more and it has nowhere to go. Essentially, you’re trying to function while wearing a plastic bag. Not cute!" she said.

This is bad news for your skin health, too. Without the ability to "breathe," these fabrics keep you warm and sweaty. "This may result in overheating and fungal overgrowth on the skin," explained Dr. Nava Greenfield, a board-certified dermatologist who calls out nylon specifically as a fabric to avoid.

It's not just a problem for you: Our plastic clothes are bad for the environment, too. Every time we do a load of laundry full of synthetic fabrics, thousands of plastic microfibers break off and make their way into the wastewater and ultimately the ocean.

In any season, denim jeans can become the default choice for their ease of wear, but it's not always a good choice for hot weather. "An unexpected summer offender is denim, generally heavyweight with no breathability or stretch unless it's been mixed with elastane," Rice said. Plus, denim's typical dark color absorbs heat, unlike light colors, which can keep you cooler.

To make denim work for hot days, choose loose styles in white or light wash color. Also look for those with a lighter weight than your winter jeans — 12 ounces or less is good to aim for.

While cotton is typically recommended for summer wear, there is an instance where it should be skipped: socks. Cotton is a natural fiber that is breathable and airy, typically lightweight and keeps you cool. But it also holds on to moisture — which is good for getting sweat off your body, but not so good for your feet. When worn as socks, cotton turns them into a haven for smelly, wet feet, which can lead to fungal growth.

In these cases, merino wool can keep feet dry and odor-free. Even polyester can be a smart choice thanks to its moisture-wicking properties (just keep the polyester to the socks, and remember that pure polyester can hold on to smelly feet odor).

Not surprisingly, wearing your winter wool during the summer won't end well. Wool is a cold-weather staple due to its ability to keep us warm. It's a natural fabric that has insulation properties to keep in heat, as well as some water resistance to prevent rain or melted snow from reaching our skin. Typically, clothes like sweaters and coats are made with wool, and it's unlikely you would wear those out in the heat.

But some of the very features that make wool perfect for cold weather can make it an ideal choice for summer, with some considerations. A lightweight wool like merino, which is made with thinner fibers, can effectively pull moisture away from your body and help keep a lower body temperature. "If you’re taking part in sport, a natural winner is merino wool ― the lightweight fibers draw moisture away from skin and literally evaporate it into the air," Rice said. Look for merino wool sleeveless shirts for the best of both worlds.

It might seem like most clothing is a no-go (and given polyester's majority stake, you’re not all wrong), but there are several fabrics and clothing features that are ideal for summer.

"Generally I’d advise sticking to natural fabrics where possible: linen, cottons and jerseys," Rice said. (You should check the label on jersey, though: Some versions are synthetic, and others are natural.)

"And while these fabrics might initially seem expensive, with good care and wise fashion choices, you can select heat-wise pieces that will last summer after summer," Rice added.

How that fabric looks and fits matters, too. "Aside from the actual fabric, clothes styles will come into play," Greenfield said. "Lighter color fabrics will not absorb heat as much as darker colors. Loose fabrics will allow the most air to flow across the skin."

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