How does humidity affect my skin?

What does humidity do to the skin barrier?

The stratum corneum, your skin's outermost layer, protects against water loss and substances entering from outside. Humidity influences skin hydration, elasticity and how easily skin responds to mechanical stress. The barrier also adapts to changes in humidity, so the effect involves more than whether the air feels damp.14

More humidity does not simply mean a stronger barrier. High humidity has been linked to slower barrier repair and lower levels of natural moisturising factor, substances that help skin retain moisture. In laboratory grown human skin, lowering humidity to 50% improved barrier properties in one experiment. In another, lowering humidity from 90% to 60% changed the developing skin layers without substantially changing the barrier's fat composition or arrangement. Those laboratory settings are not humidity targets for your home.14

Does humidity make skin oily?

Hot summer conditions can bring increased oil production as well as sweating. Sweat and sebum are different: sebum is the oily substance made by your skin's glands. A sweaty face is not, by itself, evidence that your oil glands are producing more oil. The practical concern is the mixture of sweat, oil and bacteria on the skin, particularly under products or clothing that contribute to clogged pores.356

Can humidity cause acne?

High humidity can trigger or worsen acne, particularly if you already have acne prone skin. Acne starts when hair follicles, the small openings that hold hairs, become blocked with material such as sebum, dead skin cells and bacteria. In hot weather, sweating, friction and irritation can contribute to that process. Sweat alone is not the whole explanation.56

Humidity is one trigger among several. Hormones, family tendency and cosmetics that block the skin can also contribute. Breakouts can affect the face, neck, chest and back. A pattern that worsens under a tight hat, sports helmet or sweaty clothing gives you something practical to change, but persistent acne needs more than a weather forecast.26

How should I change my skincare in humid weather?

If heavier creams are contributing to clogged pores, switch to a lighter moisturiser rather than dropping moisturiser altogether.5

1. 1Before exercise, remove makeup and wash your face with a gentle cleanser. Heavy makeup mixed with sweat can contribute to blocked pores.
2. 2Moisturise in the morning and at night. Choose a lighter texture if thick creams feel excessive in hot weather, and look for products labelled noncomedogenic, meaning formulated not to clog pores.
3. 3Before going outdoors, apply a broad spectrum, water resistant sunscreen with SPF 30 or higher to uncovered skin. Reapply every two hours and after swimming or sweating, and use shade and protective clothing.
4. 4While sweating, gently blot your skin with a clean towel. Avoid rubbing or wiping repeatedly, which can irritate skin and contribute to breakouts.
5. 5After exercise, shower and change into clean clothes. If a shower is not possible, wash your face with a gentle cleanser.
6. 6After a shower or bath, apply a fragrance free moisturiser within five minutes to help trap water in the skin.

Sweaty clothes and towels count too

Wear loose, breathable clothing rather than tight items that rub against your skin. For exercise, fabrics such as nylon or polyester can move sweat away from the skin and dry quickly. Wash sweaty hats, headbands, towels and clothes before reusing them. Clean shared exercise equipment before and after use, and use a clean towel to pat away sweat. Shower after extended time outside as well as after workouts.357

Does humidity help dry skin?

Humidity influences hydration, but humid outdoor air does not prevent dryness from sun exposure, pools or air conditioning. Moisturiser traps water in skin; a humid forecast has not volunteered to do the whole job. Keep moisturising when your skin feels dry instead of assuming muggy weather makes the step unnecessary.3

Use a mild cleanser and warm rather than hot water. Antibacterial or deodorant soaps and body washes can be drying. Rinse and wash after swimming, and reapply moisturiser after washing your hands or whenever skin feels dry. If air conditioning makes your home too dry, turn the thermostat up. Cooling can help with heat related sweating, but excessively dry indoor air creates a different problem.3

Are those bumps acne or heat rash?

Heat rash and sweat related pimples can look similar. Heat rash happens when blocked sweat ducts trap sweat beneath the skin and typically feels prickly, burning or itchy. Pimples involve blocked pores and inflammation. Keep skin cool and reduce heavy sweating if heat rash is a concern; fans, cool showers and exercising during cooler hours can help.35

What if changing the routine is not enough?

For acne, salicylic acid helps remove dead skin cells that can block follicles, while benzoyl peroxide targets bacteria involved in acne. Lower concentrations and wash forms of benzoyl peroxide are less irritating. Sensitive skin needs particular care: benzoyl peroxide can irritate, and using it alongside other drying ingredients such as salicylic acid can add to the problem. Do not pop pimples.567

There is no fixed recovery time for humidity related skin changes. Arrange a dermatology appointment if breakouts are not improving or a rash lingers or worsens. Seek help early for deep, painful lumps or scarring rather than waiting for the season to change. A clinician can distinguish acne from other causes of bumps and choose treatment for the actual problem.356