Why Sunscreen Still Matters in Winter
One of the biggest misconceptions about sun protection is that UV exposure disappears when temperatures drop. In reality, harmful rays are still very much present—and can even be intensified.
“UV rays are still very much present in the winter months and their effects can even be intensified due to thinner ozone levels, compromised skin barriers and snow or ice reflection,” Dr. Casey explains.
While UVB rays (the ones responsible for sunburns) are weaker in winter, UVA rays remain constant year-round. These deeper-penetrating rays are responsible for collagen and elastin breakdown, which leads to wrinkles, sagging, and premature aging. Snow adds another layer of risk.
“Snow reflects up to 80% of UV rays,” Dr. Casey notes, making winter sports like skiing and snowboarding especially high-risk for sun damage. Higher altitudes also mean thinner air and less natural UV protection.
Yes, You Need Sunscreen Indoors Too
If you spend most of your day inside, sunscreen still matters—especially if you sit near windows.
“UVA rays penetrate through windows,” says Dr. Casey. “Any time an individual is driving in a car or sitting by a window, UVA rays reach exposed skin.”
Even on overcast days, UV exposure doesn’t disappear. “On cloudy days, approximately 50–70% of UV rays penetrate through the clouds,” she adds.
Over time, this daily, low-level exposure adds up. “Sun damage is cumulative, so every day that an individual applies sunscreen supports skin health,” Dr. Casey explains. In fact, 90% of non-melanoma skin cancers are directly linked to UV damage, which accumulates over a lifetime.
What About Blue Light?
Blue light from screens and indoor lighting has raised concerns in recent years. While Dr. Casey notes that most blue light exposure comes from the sun—not devices—it can still contribute to hyperpigmentation and uneven skin tone.
“To protect against blue light, a tinted sunscreen containing iron oxide pigments is necessary,” she explains. This is especially important for individuals prone to melasma or discoloration.
The Right SPF (and How to Use It Properly)
Dr. Casey recommends SPF 30 or higher, explaining that SPF measures protection against UVB rays. “SPF 30 blocks about 97% of UVB rays, and once we reach SPF 30, we’re providing pretty adequate protection.”
However, most people don’t apply enough sunscreen to reach the labeled SPF. “I always tell patients to aim high,” she says, noting that using SPF 40 or higher helps compensate for under-application.
She also cautions against relying solely on SPF in makeup or moisturizer. “Those should be layered with a dedicated sunscreen formulation,” she says, and sunscreen should always be applied as the final step in a morning skincare routine.
Reapplication isn’t always necessary indoors—unless you’re near windows. In that case, Dr. Casey recommends reapplying every four hours, especially between 10 a.m. and 3 p.m. Reapplication is also essential before going outside or after sweating, since sunscreen ingredients break down over time.
Bottom Line
Winter weather and indoor days don’t protect your skin from long-term damage. Daily sunscreen use—rain, snow, or shine—is one of the most effective ways to prevent premature aging, hyperpigmentation, and skin cancer. As Dr. Casey emphasizes, consistency is key, and every protected day adds up to healthier skin over time.