Sun Damage to Hair: How UV Affects Hair in Summer, and How to Protect It
It’s widely understood that skin needs protection from the sun – but can sun damage hair in the same way?
Yes, it can – and that dry, brittle, straw-like feeling after long days outdoors is often a sign of UV damage to hair. Summer’s longer days also bring heat, light, and environmental stressors that gradually weaken the hair fibre, especially without targeted summer hair care.
Read on to discover how to protect your hair from sun damage through simple habit changes and summer hair products from our collections.
Can sun damage hair?
Sun damage to hair happens when UV rays come into direct contact with the hair fibre.
This exposure breaks down proteins within the strand and lifts the outer cuticle layer, which normally protects what’s inside. Sun damage to hair can show up as:
• Dry ends that feel straw-like to the touch.
• Split, frayed ends that look visibly worn.
• Brittle, fragile hair that snaps easily.
• Dull, flat colour that no longer reflects light.
• Frizzy hair and flyaway-prone strands that won’t sit smoothly.
• Tangle-prone sections that catch when brushing.
• Faded, brassy tones replacing fresh colour.
• Loosened, undefined curls that lose their shape quickly.
Not sure if what you’re seeing are the first signs of UV damage to your hair? Our Online Hair Diagnosis tool will help you understand what your hair is showing – and where to start.
How to prevent sun damage to hair: 4 expert strategies
Preventing sun damage to hair starts with supportive summer hair care formulas, protective styling habits, and targeted oils and serums.
Below, we’ll walk you through how to protect your hair from sun damage by making small tweaks to your routine, and with products from our collections.
1. Prime and protect your hair from heat
Heat protectants prevent heat damage when straightening your hair by coating the hair fibre: slowing how quickly heat passes into it. That same protective layer helps defend against the sun, which also exposes hair to heat throughout the day.
By reducing how much heat reaches the cuticle, heat protection helps limit moisture loss, colour fading, and surface dryness.
To this end, Kérastase's range of supportive heat-protecting products includes:
- Blond Absolu Heat Protecting Cicaplasme Primer – a leave-in treatment for blonde and lightened hair, with hyaluronic acid and antioxidant-rich edelweiss to help maintain hydration and tone under UV exposure.
- Nutritive Nectar Thermique Blow-Dry Cream for Dry Hair – combines niacinamide and plant-based proteins to smooth texture and protect strands from heat and environmental stress.
- Chroma Absolu Heat Protectant for Coloured Hair – a lightweight serum with amino acids that reinforces the hair fibre and helps maintain coloured hair when exposed to sun and heat.
2. Avoid air-drying hair in the sun
Hair is most vulnerable when wet – something that happens a lot more in summer, when swimming in salty and chlorinated waters is more common, and air-drying outdoors becomes routine. The downside is that drying strands in direct sunlight exposes the fibre to heat while the cuticle is lifted, which can accelerate sun damage to hair.
That’s why it’s important to let hair dry in shaded environments or gently towel-dry before stepping outside. Better still, applying a protectant such as the vitamin E-, hyaluronic acid-, and abyssine-enriched Chronologiste Regenerating Leave-In Treatment – shown to provide 24 hours of frizz control in 80% humidity* – helps form a barrier while your hair dries.
3. Cover up in the sun
Physical barriers are one of the most effective ways to protect hair from sun damage.
Wide-brim hats, scarves, and protective styles such as braids or buns help limit direct exposure, support moisture retention, and reduce the effects of UV on the hair fibre. They’re especially useful during long, hot days outdoors – when sun exposure is harder to avoid.
4. Reduce your exposure to other hair stressors
During summer, hair is often exposed to multiple stressors at once. Hot tools, hard water, and environmental exposure all place additional pressure on the fibre.
Limiting heat styling to once or twice a week, rinsing hair with fresh water after swimming in salt or chlorine, and using protective products beforehand can help reduce this cumulative impact, and manage overall sun damage to hair.
How to repair sun-damaged hair: 4-step summer hair care routine
Already noticing dryness, fading, or roughness in the warmer months?
Learning how to repair sun damaged hair starts with moisture, smoothness, and strength within the fibre – in other words, rebuilding what UV exposure has taken away.
With the right routine, you can fix heat-damaged hair even after a summer of exposure. So read on for our simple four-step summer hair care routine.
1. Smooth cuticles with a hair oil
One summer hair product you’ll be reaching for daily is hair oil. It helps protect lengths from moisture loss, keeps frizz in check, and makes sun damage to hair easier to manage.
Our Elixir Ultime Refillable Hair Oil coats the cuticle with nourishing oils to support strength and shine. Use it ahead of blow-drying or before heading outdoors. Alternatively, press a small amount into dry ends during the day to reduce friction when brushing, and keep hair feeling soft and silky.
2. Switch to an ultra-hydrating shampoo and conditioner
Sun exposure to hair leaves behind residue, dryness, and a rough surface. That’s why the best shampoo for sun-damaged hair needs to cleanse thoroughly, without removing what little moisture remains – and why conditioning is vital to help nourish and hydrate the fibre.
We recommend our Gloss Absolu Hydra-Glaze Illuminating Shampoo to lift away build-up from the scalp and lengths, and leave your hair feeling lighter and less coated after washing. Following it with the Gloss Absolu Insta Glaze Conditioner then helps the fibre retain moisture through the mid-lengths and ends, making hair easier to detangle and style.
Both are formulated with hyaluronic acid to help the fibre hold water, glycolic acid to remove build-up at the scalp, and wild rose oil to leave hair looking glossy and shiny, with a mesmerising floral scent.
3. Use hair masks to replenish lost moisture
When hair feels stiff, tangles easily, or looks dull after repeated sun damage to hair, a hair mask delivers a higher concentration of conditioning ingredients than daily products.
Our Première Repairing Mask for Damaged Hair is suited to strands weakened by UV and chemical processing. Formulated with peptides – amino acids that help support weakened areas of the fibre – it works through the mid-lengths and ends to reinforce fragile sections of the hair: helping strengthen hair and stop breakage.
If dryness is already a concern, Nutritive Masquintense Hair Mask for Dry Hair focuses on hair exposed to summer conditions. Its lipid and glycerin blend helps the fibre hold water after washing, so strands feel less rigid and detangle easily.
4. Trim split ends
Once the hair fibre splits, the damage continues travelling upward – making your strands harder to style evenly. Regular trims help remove split ends, maintain shape through the lengths, and enable more effective results from your conditioning products.
Now that you understand sun damage to hair, take your summer hair care further by learning what hair gloss does for your hair.
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