When you’re gearing up to go outside in hot weather months, wool probably isn’t the first fabric you think of. Most people turn to synthetic tees made of polyester, nylon or rayon. But Merino wool and Alpine Merino wool (often referred to as just “Alpine wool”) have absorbent fibers that help you regulate your body’s temperature and keep you cool.

Merino wool comes from Merino sheep — a specific breed known for their fine and soft wool. These sheep are primarily raised in Australian and New Zealand. Alpine wool typically refers to wool sources from sheep living in alpine regions (like the Alps and Europe) that belong to various breeds.

Both wool types are also a top pick for a lot of summer hikers — especially for strenuous hikes where a rise in temperature can increase your body heat throughout the day. And it’s not just about staying cool. It’s also about staying dry, fresh and protected from the elements.

The natural properties of Merino wool and Alpine wool, such as its ability to wick moisture, resist odors, and provide UV protection, make it a standout option compared to synthetic materials.

Wool Adapts to the World Around You

Merino and Alpine wool are fascinating in the way they work. The fabric keeps you cool when you’re hot and warm when you’re cold. Scientists call this thermoregulation.

Thermoregulation is the body’s ability to maintain its internal temperature within a certain range. For example, a wool shirt with thermoregulation can help a trail runner stay comfortable by wicking away sweat and insulating them in cool weather, while also allowing heat to escape when it’s hot outside.

Imagine you’re heading out on a trail on a hot summer day with a wool shirt designed for thermoregulation. As you start running, your body temperature rises, causing you to sweat. The shirt’s thermoregulation properties kick in, wicking away the sweat from your skin and keeping you dry and preventing overheating. The wool’s natural breathability allows for airflow, aiding in cooling your body down. This way, despite the scorching temperatures, you remain comfortable and can focus on your run without feeling excessively hot or sweaty.

The IBEX 24 Hour Short Sleeve Crew is one of my favorite Merino wool tees for trail running in my home state of Montana. Product engineers designed this tee to maximize airflow and keep you cool. This fabric is known as MECool fabric and is 100 percent Merino wool sourced from Australia. IBEX uses a proprietary steaming process that makes the material feel cooler to the touch and it’s versatile in various climates.

This shirt effectively pulls moisture away from your body — allowing for quick evaporation and so you stay dry even during strenuous hikes. On cool summer nights (as the sun sets), I frequently grab for my IBEX zip up Shak Hoodie made of 100 percent Merino Wool Ponti. Ponti is the style of tight knitting that makes this hoodie so smooth.

Whether it’s winter or summer, merino wool is never too hot, never too cold, and usually feels just right.

Wool Doesn’t Smell

Another standout feature of Merino and Alpine wool is its natural resistance to odors. The fibers contain lanolin. Lanolin is a natural wax produces by sheep to help protect their wool and skin from the elements. Since lanolin is in the wool fibers, the fabric is moisture resistant. The amount of lanolin varies per manufacturer depending on how workers process the wool.

These types of wool also have antibacterial properties that prevent the buildup of odor-causing bacteria. This is a significant advantage for multi-day hiking trips in hot weather where your access to laundry facilities is limited.

Even shirts with just some Alpine Merino wool features like the reactive Salewa PUEZ Merino Hybrid Women’s T-Shirt incorporate this wool to provide an extended period of freshness. You can wear this hybrid shirt over and over — even with intense workouts — without needing to wash it all the time.

“Our Alpine Wool is sourced from the mountain regions of South Tyrol, nearby Salewa’s global headquarters. Wool has a long tradition in the South Tyrol region of Italy, as the material has been used for centuries because of its robust performance properties,” said Michael Casarrubia, Oberalp Group’s marketing manager.

He added that Selewa’s Alpine Wool garments provide natural temperature regulation, moisture-wicking properties, odor resistance and comfort.

“This specific wool is known for being soft and non-itchy, making it ideal for wearing directly against the skin for both casual or performance activities,” said Casarrubia.

This is a solid reason to add Merino or Alpine Merino wool to your gear.

Wool Offers UV Protection

Merino and Alpine wool also offers natural UV protection, shielding your skin from harmful sun rays. This is particularly important during summer hikes when the sun is at its strongest. The fabric’s ability to block UV rays reduces the risk of sunburn and skin damage, allowing hikers to enjoy longer periods outdoors safely.

Imagine you’re on a scenic waterfall hike to Abrams Falls in Great Smoky Mountains National Park. A merino wool T-shirt would be an ideal choice. The trail, known for its views and refreshing water cascades, requires a comfortable and protective outfit. Merino and Alpine wools give you a combination of breathability, odor resistance, and UV protection so you’re protected throughout your adventure.

Top Recommended Wool Tees for Summer

Whether you’re trekking through the mountains or enjoying a serene waterfall hike, Merino and Alpine wool are your go-to fabric for comfort and performance.

• Best Overall Merino Wool shirt: Icebreaker Tech Lite Crew II T-Shirt
• Best Budget Merino Wool blend shirt: Wander Wool Shirt
• Best Luxuriously Soft Merino Wool blend shirt: IBEX 24-Hour Short Sleeve Tee
• Best Reactive Alpine Merino Wool hybrid shirt for all-day Hiking: Salewa Purez Merino Hybrid Women’s T-Shirt

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Suzanne Downing is an outdoor writer and photographer in Montana with an environmental science journalism background. Her work can be found in Outdoors Unlimited, Bugle Magazine, Missoulian, Byline Magazine, Communique, MTPR online, UM Native News, National Wildlife Federation campaigns and more.