Rylee Drew checks her weather app religiously—not for the temperature but the UV index. For her, the higher the reading, the better, so she can maximize her time in the sun. On her Instagram feed, she proudly sports her bikini tan lines to her 188,000 followers.

She’s 15.

“Some of the influencer girls she’s friends with get spray tans,” said her mom, Kayla Drew, who manages Rylee’s Instagram account. “She worked hard for it all summer.”

After years of skin care obsessives preaching the gospel of sun protection, extreme tanning is back. The UV index, developed in the 1990s to help people take precautions against excessive sun exposure, is now being used by some for the opposite purpose: to identify when tanning will produce the most dramatic effect. While some, like Rylee, take care to apply SPF 50 before basking in direct sunlight, others have promoted using little to no protection, defying recommendations from health and environmental authorities who say that sunscreen is safe and effective. Call it “tanmaxxing.”

Twitter co-founder Jack Dorsey, who released an early version of an UV tracking app called Sun Day in July that estimates vitamin D intake, recently said on X that he does not use sunscreen. Reality star Kristin Cavallari sparked conversation when she said on a 2024 episode of her podcast that she doesn’t wear sunscreen and asked her doctor, who was her guest on the show, to explain why it may not be necessary. Cavallari later said she was not advising others against wearing sunscreen and that she does apply SPF to her face and wears hats when she’s on vacation.

Marisa Garshick, a dermatologist and clinical assistant professor of dermatology at Weill Cornell Medicine, is concerned by the way some people are using these tracking apps.

“It’s the exact opposite of what we tell patients. Look at the UV index and avoid it when it’s high,” she said. “Certainly not something we’d ever think people would be using to help encourage tanning.” There is well-established, research-backed medical consensus that sun exposure is linked to premature skin aging and skin cancer. High UV days raise the risk of those conditions.

Parents have expressed a mix of concern and amusement at their teenagers’ sudden obsession with ultraviolet rays. “Does anyone else’s teenage daughter only like cheerleading, Megan Moroney and knowing what the UV index is for the day?” one dad asks on TikTok. On the actress Jana Kramer’s podcast, “Whine Down,” she and friends discuss how teens in their lives are always checking the UV. “I am literally fighting my 13-year-old to put on sunscreen,” Kramer’s friend Kathryn Woodard says, on a July episode. Kramer, for her part, says she does not routinely put sunscreen on her children. “What’s worse, the burn or the suntan lotion?”

Jill Steury, a mom of four in Ohio, said her 16-year-old daughter has been “constantly” checking the UV index, opting to be in the sun when it’s high, at around 9 or above.

“She wears little to no sunscreen,” Steury said, despite efforts to get her daughter to apply protection. Once, on a family vacation in Florida, her daughter burned so badly that she had to miss several beach days, she said.

“We were sitting in baby oil back when I was her age,” she said. “We were chasing the sun. They’re just chasing this UV index. There’s progress in knowledge but not in behavior.”

Riley Davenport, a 17-year-old in Georgia, said she first heard about the UV index from friends in middle school. “When they started talking about it, I started looking at it, too,” she said, “and I’m like, Oh, this is probably why they’re a lot more tan than me, because they’re actually going out in the peak of the day,” She said she uses her phone’s weather app to check the index.

“If it’s a 7 or hotter, I’ll plan to lay out,” Riley said. “I only wear sunscreen on my face sometimes,” she said, adding that she’s seen people online talking about chemicals in sunscreen causing cancer.

Influencers have spread misinformation about sunscreen causing skin cancer. Recalls of certain spray sunscreens containing benzene, a chemical that can cause cancer, have bolstered distrust in SPF.

“There is a sunscreen out there no matter what your skin type or skin needs are, or even regardless of what your other needs may be,” said Garshick, the dermatologist, who stressed that no studies have shown that sunscreen causes cancer. Moreover, she said, the amount of sunscreen used by most people shouldn’t affect vitamin D absorption, or cause insufficiency. “It’s not a reason not to protect yourself from the sun,” she said. “UV damage contributes to not only skin cancer but skin aging. A lot of these people who are focused on what their skin looks like and getting a glowy tan now, might not be happy if they end up with wrinkles and sun spots down the line.”

Cassandra Freeman, 31, has been tracking the UV index since college—both to tan effectively and avoid damage. “In the summer, when I have the opportunity to be, I want to be tan,” said Freeman, who lives in Phoenix and works in tech.

Lately she’s been using an app called UV index, which shows her the forecasted index and her sunburn risk. “It allows me to put in my skin type so it knows how much my skin can take so that it can forecast how long ’till I burn,” she said. The app gives recommendations for how much SPF to wear.

“I wear more SPF on my face because I want to get a tan, but I don’t want to do excessive damage or anything,” Freeman said.

Will Anderson, the CEO and co-founder of Tanning Club, which makes retro-inspired tanning lotion, sunscreen and after-sun products with low to no SPF, said his company is seeing rising interest in tanning. The company has been rolling product after product this year, selling through retailers like Revolve, Amazon, Anthropologie, as well as some luxury resorts.

“Our whole hypothesis behind this was, there’s a neglected consumer out there that likes to get tanned from the sun. That person has been forgotten and it has almost been taboo to market a product for them,” he said. Its $36 Tan de Soleil Orange Tanning Balm with SPF 6 is the company’s bestselling product. (Its highest-SPF product is SPF 30.)

“We’re not promoting sun, we’re just presenting our products to the people that want to get tan because we don’t want to ruffle any feathers,” a very-bronzed Anderson said via Zoom from Newport Beach, Calif.

“We do believe in SPF which is why we offer it in our assortment but we know that people are still tanning and we make products with that in mind,” Anderson said. “On the back of our bottles, it says ‘bronze responsibly.’”