When the temperature drops and sweaters come out of storage, sun protection is often the first step relegated to the back of the medicine cabinet. After all, if the sun doesn’t feel hot and the sky looks gray, do we really need it?
From a clinical standpoint, the answer is an absolute yes.
Skipping sun protection during the cooler months is one of the most widespread skincare misconceptions. Here is the science behind why ultraviolet damage doesn't take a seasonal break, and how to adjust your routine for fall and winter.
1. The Tale of Two Rays: UVA vs. UVB
To understand why winter photoprotection matters, it helps to distinguish between the two primary wavelengths of ultraviolet radiation reaching the skin:
UVB (The Burning Rays): UVB intensity fluctuates sharply throughout the year. It peaks during spring and summer midday hours and causes acute sunburn. Because UVB levels decrease in the winter, many people mistakenly assume sun damage stops altogether.
UVA (The Aging Rays): UVA accounts for roughly 95% of the UV radiation reaching the Earth's surface, and its level remains relatively consistent all year long. UVA penetrates deep into the dermis, accelerating collagen breakdown, elastin degradation, and long-term DNA damage.
Crucially, UVA rays pass directly through clouds and standard window glass. Whether you are sitting near an office window or driving on an overcast afternoon, your skin is still exposed.
2. Snow Reflection and Altitude
If your winter plans involve snow sports or mountain travel, UV exposure can rival—or even exceed—a midsummer beach day:
The Reflection Factor: Typical surfaces like grass, soil, or water reflect only 10% to 15% of UV radiation. In contrast, fresh snow reflects up to 80% to 85%. This creates a double dose of exposure, bouncing rays upward to target areas rarely hit directly, such as under the chin, the jawline, and the nose.
Elevation Effects: Atmospheric filtering diminishes at higher elevations, causing UV radiation levels to rise roughly 4% to 10% for every 1,000 meters of altitude gained.
3. Adapting to Winter Skin Barrier Changes
A lightweight, mattifying gel or fluid that works well during humid summer months can leave skin feeling tight and dry once cold winds and artificial indoor heating take hold.
Low ambient humidity increases transepidermal water loss (TEWL), impairing the skin barrier. Transitioning to a richer, cream-based vehicle provides vital barrier support:
Barrier-Replenishing Lipids: Look for formulations that incorporate ceramides, squalane, plant oils, or fatty acids to reinforce the lipid matrix and lock in moisture.
Humectant Hydration: Formulas containing glycerin or hyaluronic acid help draw water into the stratum corneum, combating winter flaking.
Mineral vs. Chemical Filters: For skin prone to windburn, dryness, or vascular reactivity during colder months, mineral filters (zinc oxide and titanium dioxide) are often better tolerated because they are inert and less likely to sting a compromised skin barrier.
4. Balancing Winter Resurfacing Treatments
Fall and winter are common times to introduce corrective dermatological regimens:
Prescription and over-the-counter vitamin A derivatives (retinoids)
Chemical exfoliants (alpha and beta hydroxy acids)
In-office procedures (chemical peels and laser resurfacing)
While these therapies help reverse summer photodamage and uneven pigmentation, they also accelerate cell turnover and temporarily thin the outermost protective layer of dead skin cells. Without consistent daily broad-spectrum coverage, treated skin becomes significantly more vulnerable to rebound hyperpigmentation and phototoxic reactions.
Practical Winter Habits
Maintain Broad-Spectrum Coverage: Apply a broad-spectrum formula rated SPF 30 or higher every morning as the final step of your skincare routine.
Cover High-Risk Zones: The ears, neck, upper chest, and back of the hands receive continuous cumulative exposure throughout the year and are frequent sites of photoaging.
Protect the Lips: Cold wind combined with UV exposure frequently leads to severe chapping and actinic cheilitis; keep a dedicated lip balm with broad-spectrum UV filters on hand.
Reapply Outdoors: If you are outside for winter sports or extended recreation, reapply every two hours, exactly as you would in midsummer.