Scalp hair can show seasonal changes, but the evidence does not prove that everyone’s hair grows faster in summer. Small studies have found changes in the proportion of hairs in different growth-cycle phases, with shedding often increasing in late summer or early autumn. That is different from showing that each scalp hair grows more quickly in warm weather.
So, if your hair seems to grow faster in summer, the change may be real for you—but it may also reflect less breakage, different styling, or normal variation in the hair growth cycle.
What does the research show?
A frequently cited 1991 study followed 14 men in Sheffield for 18 months. The proportion of scalp follicles in the active growth phase peaked in March and fell to its lowest point in September, while shedding peaked around August and September. Beard and thigh hair showed faster growth in warmer months, but the study did not establish that scalp hair shafts grew faster in summer.
Other studies have also found seasonal changes in scalp-hair cycling. Research involving 41 Chinese volunteers recorded more resting-phase hairs around August and September, while a long-term study found a higher proportion of resting hairs at the end of summer and beginning of autumn. These patterns suggest seasonality, but they vary between individuals and do not support a universal “summer growth spurt”.
Why might your hair look longer or fuller in summer?
Less breakage and different styling
Wearing hair loose, using less heat styling or choosing protective summer styles can improve length retention. When fewer ends snap, hair may appear to gain length more quickly even if the follicles are growing at their usual rate.
Normal hair-cycle variation
Each follicle follows its own cycle of growth, transition and rest. Seasonal shifts in the proportion of follicles in each phase may affect how full the hair looks and how much you shed, but the effect will not be the same for everyone.
Changes in routine
Holiday schedules, washing frequency, diet, activity and stress can all change during summer. These factors may affect how hair looks and feels, but they have not been shown to explain seasonal scalp-hair growth on their own. Heat-related changes in circulation and extra daylight should therefore be treated as hypotheses rather than proven causes.
Does vitamin D make hair grow faster in summer?
Vitamin D has biological roles in the body and low levels may be considered when a clinician investigates some hair-loss concerns. However, more sun exposure does not automatically mean faster hair growth, and intentional unprotected UV exposure is not a safe hair-growth strategy.
If you are concerned about vitamin D deficiency, speak to a GP or pharmacist rather than relying on sun exposure or starting high-dose supplements. Follow NHS sun-safety advice and protect exposed scalp skin.
Why can shedding increase after summer?
Several studies have observed more hairs entering or reaching the resting and shedding phases around late summer and early autumn. This can be a normal seasonal pattern, but sudden, heavy or persistent shedding should not automatically be blamed on the time of year.
Seek professional advice if hair loss causes visible thinning or bald patches, follows illness or a major dietary change, or continues for several months. Our guide to telogen effluvium explains other common triggers for temporary shedding.
How to care for your hair in summer
Protect the scalp from sunburn
A hat or scarf can shade exposed scalp and help protect the hair. Use suitable sunscreen on visible areas of skin, including a wide or thinning parting, and follow the product directions.
Reduce UV and heat damage to the lengths
Sunlight can affect hair proteins, colour and fibre condition. A review of hair photoageing describes increased porosity, surface roughness and loss of mechanical strength after light exposure. Limit prolonged exposure where practical and avoid adding unnecessary high-temperature styling.
Rinse after swimming
Rinse hair after swimming in a pool or the sea, then cleanse and condition according to your hair type. Detangle gently, particularly when the hair is wet, to reduce mechanical breakage.
Focus on hydration and condition
Sun, wind, swimming and styling can leave the lengths feeling drier. A gentle wash routine and conditioner can support softness and manageability. A cosmetic mask can also help hair feel smoother, although it cannot change the follicle’s growth rate.
A practical Hair Gain summer routine
For seasonal cosmetic care, use Hair Gain’s Hydrating Shampoo & Conditioner for gentle wash-day care and the Hair Mask when the lengths need extra conditioning. Scalp Foam is a moisturising option for a comfortable, non-irritated scalp.
These products support cosmetic condition and routine care; they do not prove or create faster seasonal hair growth. Supplements should only be used as directed and are not a substitute for a balanced diet or medical advice about hair loss or deficiency.
Frequently asked questions
What month does hair grow fastest?
There is no single proven fastest month for everyone’s scalp hair. One small UK study found the highest proportion of scalp hairs in active growth in March, not midsummer, while shedding peaked around August and September.
Does hot weather make hair grow faster?
There is no good evidence that heat alone accelerates scalp-hair growth. Hair can appear to retain length better when styling and breakage patterns change.
Is summer hair shedding normal?
A modest seasonal increase in shedding can occur, particularly around late summer or early autumn. Marked, patchy or prolonged hair loss needs professional assessment.
Does hair grow faster in summer? Final thoughts
The most accurate answer is: possibly for some people, but it is not proven as a universal rule. Research supports seasonal variation in scalp-hair cycling and shedding, not a simple guarantee of faster growth in hot weather. Protect the scalp, reduce damage and focus on consistent year-round care rather than trying to force a seasonal growth spurt.
