Summer can be filled with fun adventures in the sun—which may not be as fun for our hair if we forget about protecting it. While most of us are diligent about SPF for face and body, we often forget that our scalp is skin, too—which means it also needs protection, hydration, and rest from environmental stressors.
From UV radiation to chlorinated pools, seawater, and sweat, summer brings a unique mix of internal and external factors that can compromise hair structure, alter scalp health, and trigger dryness, breakage, or even shedding.1 The good news? With a precautionary and personalized approach, you can enjoy summer without sacrificing your hair health.
Sun Exposure and UV Rays.
Most are surprised to learn that sun exposure doesn't just fade hair color, it can also physically alter the structure of your strands. Harsh sun rays that we can’t see directly, like ultraviolet (UV) radiation, including UVA and UVB, can damage both the scalp and hair shaft.2
A 2022 study found that UV exposure significantly reduces protective fatty acids called ceramides in hair, increasing brittleness and split ends.2 Ceramides typically act as natural moisturizers, locking in hydration in skin and hair. A decrease in these fats leaves hair drier and more vulnerable to environmental damage.
It's not just the hair shaft that’s at risk. UVB radiation can also affect the hair follicle itself, accelerating shedding and reducing cell activity during the growth phase of the hair cycle.3 UVB radiation may also contribute to hair protein breakdown, while UVA is found to have an effect on hair color, like lightening after time in the sun.4
Protect your strands:
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Wear a wide-brimmed hat when in direct sunlight to protect both scalp and strands.
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Seek shade during peak UV hours (10 a.m. to 4 p.m.).
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Use UV-protective hair products (like leave-in products with antioxidants or filters).
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Emerging research suggests caffeine in topical hair or scalp products may protect the outer layer of hair follicles from UV-induced damage.5
Chlorine and Salt Water.
The combination of sunshine and swimming can be problematic for your hair, especially if it’s dyed or naturally porous. Chlorine is a strong oxidizing agent that breaks down keratin, the protein that gives your hair structure and strength. This can lead to weakened cuticles and hair that's rough, brittle, and prone to breakage. High-porosity hair tends to absorb water quickly—and lose it quickly, too, which can make hair even more prone to dryness, frizz, and tangling.
Chlorine can also degrade melanin, leading to hair discoloration.1 And when chlorine is combined with UV exposure, like on a sunny day at the pool, the damage intensifies.6
Seawater is gentler than chlorine, but can still be damaging. Its salt content can dehydrate hair and make it harder to detangle, especially if it’s been dyed or bleached. In one study, bleached hair immersed in seawater became more tangled, duller, and more difficult to comb compared to hair that wasn’t bleached or dyed.7
Before you dive in:
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Rinse hair with fresh water (like an outdoor shower) before and after swimming. This saturates the hair shaft so it absorbs less chlorine or salt.
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For curly or coarse hair, apply a hair oil before swimming to prevent excessive absorption of chlorinated water. For fine hair, use a lightweight leave-in conditioner to protect it before going in the water.
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Wear a swim cap to reduce chlorine penetration.
Heat and Humidity.
Sweating in the heat can alter your scalp’s pH and microbiome. A warm, moist scalp encourages overgrowth of Malassezia, a type of yeast that’s often naturally present on our scalps, and can lead to flaking, irritation, and even hair thinning if left unresolved.8 Malassezia feeds on sebum, the oily substance produced on the scalp, which produces irritants that further throw off the scalp’s “normal” balance. Scalp irritation is a common, but often overlooked, trigger for excessive shedding.8
Humidity also affects hair’s physical structure. One study found that higher moisture content in humid air increased hair fiber weight, changed its frictional properties, and led to cuticle swelling.9 Translation? Your hair feels frizzier, heavier, and more tangled when the humidity is high.
These effects are especially pronounced in curly or textured hair, where strands are more susceptible to moisture-induced changes at a structural level. Think of your hair like a tiny skyscraper. Keratin is a type of protein that makes up the core of the structure, while lipids are fatty substances that hold the keratin building blocks together. One study confirmed that curly hair becomes more fragile and changes its behavior in high-humidity environments.10
To balance the scalp and protect strands from humidity:
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Rinse your scalp with cool, filtered water after sweating.
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Use microbiome-friendly scalp exfoliants to remove sweat buildup, like Nutrafol’s Build Up Blocker Hair Mask, designed to dissolve pore-clogging oil and product build-up with a gentle exfoliation of the scalp.11
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Beat humidity by using a deep conditioning treatment with protective ingredients like aloe vera for curly or coarse hair. For finer hair, opt for lightweight shampoos and volumizing conditioners with nourishing ingredients like hydrolyzed proteins. Our physician-formulated Root Purifier Shampoo cleanses without stripping the scalp, while our lightweight Strand Defender Conditioner, formulated with glucose fibers and vegan protein, replenishes moisture.12,13
Sun and Sleep.
As daylight hours start to increase in spring and continue through summer, we may experience a shift in circadian rhythm and hormone production, impacting our sleep cycle, which may lead to waking earlier or feeling more energized through the day.15 If sleep is impacted too significantly, though, changes related to poor sleep, such as elevated cortisol, can start to influence hair health.14
To support your sleep and protect your hair health:
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Ensure you’re still getting enough sleep each night; 7+ hours is ideal.16
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Keep your bedroom dark with blackout curtains or use an eye mask to reduce the impact of excess light during early sunrises or late sunsets.17
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Keep your room cool; some studies mention temperatures between 60-70℉ are ideal for quality sleep. And bonus—using a fan or A/C in the room can act as white noise that may also help with sleep.17
The bottom line:
There’s no one-size-fits-all routine for summer because your hair’s exposure, health history, and natural texture all influence its resilience. The cumulative environmental impacts on your hair and scalp all matter. Whether your hair is dyed, curly, fine, or prone to oiliness, your summer care plan should be customized to you.
Think of your hair like your skin: it needs shielding from the sun, protection from pollutants, hydration after heat, and time to recover. With a few thoughtful steps like sun hats, fresh water rinses, and scalp TLC, you can enjoy the best of summer while keeping your hair healthy and strong.