Why do my pores look bigger in hot weather?

Studies from Korea link hot weather with more oil and more visible pores. A Korean study that measured facial oil in every season for a year found summer was the season with the most oil, and that the forehead, nose and chin had more oil than the cheeks, and a study of 100 Korean men measured more visible pores in summer than in winter. Oil is one of the three main causes of large-looking pores that dermatologists describe, alongside less firmness around the pore and larger hair follicles, and a Thai study found that the amount of oil did not track pore size. In a Korean study, older people and men tended to have larger pores. For care, the NHS suggests gentle washing twice a day, non-comedogenic products and sunscreen when you are out in the sun.

What is a pore, and what makes it look large?

A pore is the opening of a hair follicle on the skin. Each one is linked to an oil gland, which releases oil, called sebum, through the opening onto the skin surface.

The three main causes

A 2016 review by dermatologists at Chung-Ang University and clinics in Seoul names three main causes of large-looking pores on the face:

The same review adds that frequent breakouts, sex hormones and your skin care routine can also affect how pores look. It also says that large pores are not a medical concern, but a cosmetic concern for a large number of people.

Other factors researchers list

A 2006 study by Roh and colleagues in Seoul lists further factors that have been linked with large pores, including sex, genes, ageing, long-term exposure to ultraviolet (UV) light and substances that clog pores.

Why do pores look bigger when it's hot?

Heat changes how much oil skin makes, and oil makes pores easier to see.

More oil in summer

The year-long study by Youn and colleagues in Korea measured oil at five places on the face in the same volunteers in each season. It found more oil on the forehead, nose and chin than on the cheeks, and summer was the season with the most oil. That is why the T-zone often looks shinier than the cheeks.

More visible pores in summer

A 2015 study of 100 Korean men aged 20 to 59 compared the same men's skin in summer and in winter.

The study was done in Korea, where winters are cold, so it does not tell us how big the change is in Thailand. It looked only at men, and the researchers worked at a private company that carries out skin testing; the study did not test any product. It shows that the same face can measure differently from one season to the next.

Sweat and shine

In hot, humid weather skin also sweats more through the day. The UK's NHS explains that spots develop when hair follicles become blocked with excess oil and dead skin cells, and suggests washing twice a day with a gentle cleanser.

Does oily skin always mean big pores?

Not always. Two studies from Asia came to different answers.

The Thai study, by researchers at Chulalongkorn University and Ramathibodi Hospital, Mahidol University, also found that the skin of women who called their skin dry held more water. It was a small study of women only. Together, the two studies suggest that oil is one factor, and that other things, such as firmness around the pore and the size of the follicle, matter too.

Do age and sex make a difference?

In the 2006 Korean study, which compared people of different ages rather than following the same people over time, larger pores were linked with more oil, older age and being male. Among those factors, oil was the strongest, followed by being male.

In women

The same study found pore size was larger around ovulation, the middle of the menstrual cycle, and the researchers concluded that hormones add to the picture in women. The 2016 review likewise lists sex hormones among the things that affect pores.

With age

The 2016 review lists less firmness in the skin around pores among the three main causes. The 2006 study lists ageing and long-term UV exposure among the factors linked with large pores.

How can I look after my skin day to day in hot weather?

The advice below comes from the UK's NHS. The washing advice is the NHS's self-care for spots and blocked pores; the NHS does not give separate advice for pores.

Washing and products

For people with spots, the NHS suggests:

• wash your skin twice a day with a gentle cleanser
• use skincare and make-up labelled non-comedogenic, meaning they are made not to block pores
• remove make-up at the end of the day
• do not scrub your skin, because this can irritate it
• do not pick or squeeze spots, because this can cause scars
• if you have spots on your body, wear loose, breathable clothing, especially when exercising or sweating

Sun protection

The NHS advises a sunscreen with an SPF of at least 30 and at least 4-star UVA protection, reapplied every 2 hours and after sweating or towel drying. The same NHS page notes that you can burn even when it's cloudy.

Wearing a face mask for long hours

A 2020 survey of people wearing face masks in Thailand by Khon Kaen University found that 54.5% reported a skin problem under the mask, most often spots (39.9%), followed by rashes and itching. Wearing a mask for more than 4 hours a day and reusing masks were both linked with more skin problems than changing the mask every day. It was a questionnaire carried out in 2020, when mask wearing was recommended for the public, so it reflects what people reported.

Putting the NHS advice into a day

For very hot days, the NHS suggests keeping out of the heat if you can, staying in the shade especially between 11am and 3pm, wearing light clothes, and cooling down with a cool shower or cool water on your skin.

For more on dry skin in summer and oily skin in the rainy season, see Dry, dull skin in summer, oily in rainy season: how to care?. For daily sun habits, see How do you look after skin day to day in a hot climate?

When should I see a doctor about my skin?

Visible pores on their own are a cosmetic concern rather than a medical one, as the 2016 review notes. If you also have spots, the NHS advises seeing a GP if:

• you have tried looking after it yourself and it is not getting better
• you have lots of spots, or the spots are deep, painful or leaving scars
• the skin is hot, swollen and red
• it is affecting your mental health

For breakouts that keep returning, see Why do I keep getting spots as an adult, and what can I do?