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SPF isn't seasonal, the marketing is.

SPF isn't seasonal, the marketing is.

Why you need sunscreen year-round, and what the science actually says.

Written by Dr. Aimee Paik, MD, board-certified dermatologist and VIZE co-founder

In short 

Yes, you need sunscreen year round. And it matters more for how your skin looks than most people realize. We think of sunscreen as a summer product because summer is when UVB is high and sunburn is on our minds, but UVA, the band behind fine lines, dark spots, and uneven tone, doesn't fall off the way UVB does in winter. It's lower, but it's still there, and it can age your skin without ever causing a sunburn. Most of the sun you'll ever get comes from ordinary days rather than vacations, which is why daily SPF does more for even tone and visible aging than almost anything else in your routine.

UV rays don't take days off, neither should you.

When we were building VIZE, we heard the same thing from almost everyone: launching a sunscreen in the fall was a mistake. It’s off-season, off-trend, and nobody buys SPF when days at the beach or pool aren’t top of mind. 

That reaction is a big part of why we exist. It didn't tell us we'd picked the wrong time of year. It told us the whole idea of a "sun season" was the problem. Somewhere along the way, sun protection got sold as something you do in the summer or on sunny vacations. A seasonal purchase instead of a daily habit.

Sunburn is only half the story.

People buy SPF in July because most people think about SPF as a tool to protect you from sunburn, but really SPF protects you from so much more than that. Getting into understanding UVA and UVB is helpful here.

UV 101: A is for aging, B is for burning

There are two types of ultraviolet rays that reach your skin. 

UVB is the shorter wavelength. It penetrates the top layers of your skin and it's what causes sunburn, along with most skin cancers. It's also the one that drops off sharply in winter, which is exactly why people relax about SPF once it gets cold. Burning is the most noticeable and extreme form of sun damage, so it's what we're all trained to think about and try to prevent.

UVA is the longer wavelength. It goes deeper, where it breaks down collagen and drives pigmentation. That's the mechanism behind fine lines, loss of firmness, and dark spots. And what most people don't realize is that none of it requires a sunburn to happen.¹

Both UVB and UVA rise and fall with the seasons, but they don't fall off the same way. UVB nearly collapses in the winter², becoming largely negligible except at high altitude, reflected off snow, or in the tropics. But UVA drops off far less steeply. Winter days can still deliver UVA at meaningful levels, and skin aging is caused by cumulative year-round UV exposure, not a single summer day.

The Sneaky UV Exposure You Get Indoors

You may be someone who is starting to feel good about working indoors all day, but not so fast. While UVB is largely blocked by windows, UVA rays can penetrate glass. Dermatology has a famous illustration of this. A truck driver photographed after 28 years on the road³, with one side of his face visibly older than the other. Same man, same age, same genetics. The only variable was the UVA coming through the driver's-side window. 

A quick note before you start worrying about every window around you: not all glass lets in the same amount of UVA. In cars, side windows tend to offer less UVA protection because they’re thinner, while windshields block much more because they’re made with laminated glass. These aging UVA rays drop off sharply as you move away from a window, so meaningful indoor exposure mainly occurs from direct sunlight through glass.

Most of the sun you'll ever get isn't a beach day

Have you ever thought about how many days a year you actually spend at the beach, or at a pool, or outside long enough to think about burning? For most, it's a handful. A few weeks if we're lucky.

Now count the mornings. The drive to work. The walk from the parking lot. The twenty minutes at school pickup. Taking the dog around the block, washing your dishes at the sink with the morning sun coming through the windows, a lunch outside. None of these daily actions register as time spent in the sun, and that's exactly why they add up. That daily exposure is what shapes how your skin ages.

In a study in Nambour, Australia of 903 adults under age 55 (mean age 39 years), subjects were randomized to apply sunscreen every day with instructions on how to apply it properly, or to the control group who used sunscreen at their discretion. Daily sunscreen users showed no detectable increase in skin aging after four and a half years. Compared to the control group who used sunscreen for mainly recreational use, daily sunscreen users had 24% less skin aging.⁴ That’s a huge difference. And it was SPF 15. The variable that mattered wasn't strength. It was consistency throughout the year.

It's not too late to start

Whatever your history with the sun, it doesn't disqualify you. Some of us have a teenage tanning bed era we'd rather not discuss...that isn't the point.

The point is what happens once you start. In a year-long study, 32 adults with existing sun damage used a photostable broad-spectrum SPF 30 every day. By the end of the year, every one of them showed measurable improvement: better skin clarity and texture, less visible pigmentation and fine lines. Daily sunscreen use actually reverses signs of skin aging.⁵

Which is why the answer to "haven't I already done the damage?" matters less than what you do from here. Starting a daily SPF habit is the single most important thing you can do for how your skin looks over time.

 

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FAQs

Do I need to apply sunscreen every day?

Yes. UV reaches your skin on ordinary days, not just sunny ones, and the exposure that shapes how your skin ages is the kind you never plan around. Daily use also consistently outperforms occasional use, even at a lower SPF.

Do I need SPF if the UV index is low?

A low UV index means low burn risk. But the index is a sunburn score, weighted heavily toward UVB. It accounts much less for UVA, the rays behind fine lines, dark spots, and loss of firmness. So a low number in the winter or early morning tells you that you probably won't burn. It doesn't tell you about the UVA reaching your skin.

Do I still need sunscreen on a cloudy day?

Yes. Clouds reduce UV but they don't block it. Roughly a third of both UVA and UVB still passes through cloud cover. In fact, some of the worst sunburns happen on cool, overcast days, when the heat is gone but the UV index is still high.

Do I need to wear sunscreen if I’m staying inside all day?

Yes. For two reasons. Glass blocks UVB but lets UVA through, so the light coming in through the window still contributes to premature aging. And most days you're outside more than you think. The dog walk, the coffee run, the ten minutes in the driveway. It adds up without you noticing.

Won’t applying sunscreen everyday make me vitamin D deficient?

While it’s true that sunlight stimulates vitamin D production by the skin, the UVB photons required to initiate vitamin D synthesis are the same UV rays that cause sunburn and skin cancer. There is no safe wavelength of sunlight that produces vitamin D without also directly causing DNA damage.

The American Academy of Dermatology (AAD) recommends a diet that includes foods naturally rich in vitamin D and/or foods/beverages fortified with vitamin D. These include oily fish, eggs, and fortified foods (dairy, cereals, orange juice). 

Outdoor activities are important for physical and mental health. Sun protective strategies, including sunscreen and protective clothing, help prevent skin damage when outdoors. 

Doesn't the SPF in my foundation cover me?

It counts for something, but have you ever measured how much you’re applying? Most people apply sunscreen at about a quarter of the amount they are supposed to, and with makeup it's usually far less. To get the SPF you see on the label, you need to apply ¼ tsp on your face and neck. Underapplying sunscreen dramatically reduces its effective protection. 

References

The content on adVIZE is for general education and is not a substitute for professional medical advice, diagnosis or treatment.