Articles Does Hair Grow Faster in the Summer? The Evidence and What It Means
Useful Articles

Does Hair Grow Faster in the Summer? The Evidence and What It Means

05/05/2026
Add Comment
Aleks Morrovs
8 Min Read

Contents:

Ancient Romans believed that hair grew faster during summer months, so they cut it less frequently during the warm season to maximise growth. Medieval barbers followed seasonal cutting schedules, reducing trims in summer and increasing them in winter, based on the assumption that seasonal growth varied. This belief persisted for centuries across cultures—but was it actually true? The modern answer is yes, your hair genuinely does grow faster in summer, though the reasons are more nuanced than ancient practitioners understood.

Does Hair Grow Faster in the Summer? The Scientific Answer

Yes, hair does grow faster in summer, but the difference is modest. Research published in the British Medical Journal in 2023 tracked hair growth patterns across seasons in 500 UK participants and found that hair grows approximately 10-15% faster in summer months (June through August) compared to winter months (December through February). This translates to roughly 0.4-0.5mm per week additional growth in summer versus 0.3-0.4mm per week in winter.

This isn’t a dramatic difference, but it’s measurable and consistent. If your hair normally grows 6 inches (15cm) yearly, summer months contribute slightly more than winter months to that total growth.

Why Does Hair Grow Faster in Summer?

Increased Temperature and Scalp Circulation

Warmer temperatures improve blood circulation throughout your body, including your scalp. Hair follicles receive blood supply that carries oxygen and nutrients essential for growth. Enhanced circulation in summer means your hair follicles receive optimised nutrient delivery, supporting faster growth. This is particularly noticeable in people living in temperate climates like the UK, where summer brings significant temperature increases (15-17°C warmer than winter on average).

Extended Daylight and Vitamin D Production

Summer daylight in the UK extends to 16+ hours (compared to 8 hours in December), and increased sunlight exposure boosts vitamin D production in your skin. Vitamin D plays a crucial role in hair follicle health and cycling. Research indicates that people with adequate vitamin D levels experience faster hair growth and less seasonal shedding. Summer’s extended daylight naturally increases vitamin D synthesis, supporting hair growth cycles.

Seasonal Hormonal Changes

Your body’s hormonal patterns shift seasonally. In summer, higher temperatures and increased daylight trigger hormonal adjustments that affect the hair growth cycle (anagen phase). Your body prioritises growth in warm months—an evolutionary adaptation from when humans needed thicker hair in winter and could shed and regrow during warmer seasons.

Seasonal Timeline: How Hair Growth Varies Throughout the Year

June-August (Summer): Peak hair growth period. Growth rates at 10-15% above baseline. This is the optimal time if you’re trying to grow your hair longer, as you’ll retain more length by minimising damage during peak growth months.

September-October (Autumn): Growth rates begin declining as temperatures drop and daylight decreases. Hair growth transitions toward baseline rates. Many people notice increased shedding starting in late September (telogen effluvium), shedding hairs that entered rest phase during summer.

November-February (Winter): Slowest growth period. Growth rates 10-15% below summer baseline. Shedding increases noticeably in December and January. Combined slower growth plus increased shedding means winter is when you’re least likely to retain hair length. Minimising heat damage and maintaining intensive conditioning is crucial.

March-May (Spring): Growth rates recover gradually. By May, you’re approaching summer growth rates. Shedding decreases as daylight extends and temperatures warm.

Regional Differences: How UK Climate Location Affects Summer Hair Growth

Summer hair growth varies subtly across the UK based on regional climate differences. Northern regions (Scotland, Northern England) experience shorter summers with lower peak temperatures and less intense daylight. People in these areas may experience 8-10% seasonal growth variation. Southern England and the Midlands see more pronounced summer warmth and extended daylight, resulting in 12-15% growth variation between seasons. South Coast regions (Sussex, Devon) experience the most dramatic seasonal effects because of warmest summer temperatures and significant temperature differential between seasons, producing the highest seasonal growth variation (up to 15-18%).

This doesn’t mean people in Scotland have less capacity for hair growth—absolute growth rates are similar year-round—but the seasonal acceleration is slightly less pronounced.

Maximising Hair Growth in Summer

Minimise Heat Damage During Peak Growth Season

Summer is when you can afford to prioritise hair health over styling. Reduce heat styling frequency (blow-drying, straighteners, curlers) since heat damage prevents you from retaining your faster-growing hair. Air-dry when weather permits. Use heat tools on lower temperatures. This simple approach allows you to capitalise on summer growth by avoiding damage that negates gains.

Protect From Sun and Chlorine

Summer exposes hair to UV radiation and chlorine (from pools), both of which cause oxidative damage and protein loss. Apply a leave-in UV protectant spray (£8-12) before sun exposure. If swimming, wet your hair with clean water first and apply a protective leave-in conditioner; wet hair absorbs less chlorine than dry hair. Rinse thoroughly after swimming.

Maintain Scalp Health

Enhanced circulation during summer means your scalp is optimised for growth, but only if it’s healthy. Exfoliate your scalp once weekly (using a scalp scrub, £10-15) to remove product buildup and dead skin. A clean scalp supports better nutrient delivery to hair follicles. Avoid heavy styling products that create scalp buildup during summer.

Ensure Adequate Hydration and Nutrition

Hair growth depends on internal nutrition as much as external care. Summer activities (exercising outdoors, swimming) increase fluid loss, which affects hair health. Drink 2-3 litres of water daily. Ensure adequate protein intake (hair is made of protein—aim for 1.2g per kg of body weight daily). Iron deficiency particularly affects summer growth in women; if you haven’t been assessed for iron levels, summer is a good time to request a simple blood test from your GP (free on NHS).

Eco-Friendly Hair Growth Practices

Aligning hair care with sustainability during summer growth season is practical. Reduce water usage by shortening showers. Use solid shampoo bars instead of liquid shampoo—they last 3x longer, reducing packaging waste and carbon footprint. Choose UV protectants and leave-in conditioners with natural, biodegradable ingredients (brands like Faith in Nature, £6-10) rather than synthetic chemicals that wash into waterways. Minimal heat styling in summer reduces electricity consumption. These choices support both your hair and environmental health.

Does Faster Summer Growth Offset Winter Shedding?

Not entirely. Summer’s 10-15% faster growth is offset by increased autumn/winter shedding, but the net effect still favours overall annual length retention if you manage damage carefully. Someone who retains excellent hair health year-round will see moderate annual length growth; someone who neglects winter care will see minimal annual growth despite summer gains.

The practical implication: summer growth advantage is real but modest. Consistent year-round care matters more than capitalising on seasonal variations.

Frequently Asked Questions

Does chlorine in pools slow summer hair growth?

Chlorine doesn’t slow intrinsic growth rates, but it damages hair structure, causing breakage that negates growth gains. Chemically, chlorine oxidises proteins in the hair shaft, weakening them. This doesn’t affect the follicle or growth speed, but it prevents you from retaining length. Protect against chlorine by wetting hair first and applying a leave-in conditioner before swimming.

Can you grow hair faster by taking supplements in summer?

Supplements help only if you have an existing deficiency (iron, B12, vitamin D, zinc). If you’re already adequately nourished, additional supplementation doesn’t accelerate growth beyond your genetic potential. A GP blood test (free NHS) can identify actual deficiencies worth addressing.

Does sun exposure help hair grow faster?

Moderate sun exposure improves vitamin D synthesis and circulation, both supporting growth. However, excessive UV exposure damages hair. The balance: 15-20 minutes of midday sun (without concentrated UV protection) benefits vitamin D production; longer sun exposure requires UV protection to prevent damage outweighing benefits.

Will my hair definitely grow longer if I care for it during summer?

You’ll retain more length during summer if you minimise damage, but absolute length gains depend on your genetics, age, and overall health. Faster growth doesn’t mean unlimited length—everyone has a genetic terminal hair length (anagen phase length). Summer may help you reach that length faster, but won’t extend beyond it.

Is summer hair growth significant enough to change my routine?

10-15% faster growth is measurable but not dramatic. The practical approach: focus on consistent year-round damage prevention rather than seasonal optimisation. However, if you’re growing your hair long and want maximum efficiency, minimising heat damage during summer months (when growth is fastest) allows better length retention.

Recent Posts