Skin Cancer in the Pacific Northwest: Why Overcast Skies Don't Protect You

The Cloud Myth: What UV Radiation Actually Does

The widespread belief that cloud cover blocks harmful ultraviolet radiation is, unfortunately, largely false. Research consistently shows that up to 80% of UV radiation passes right through overcast or lightly cloudy skies. Clouds scatter UV rays but do not absorb or block most of them—meaning that a typical Seattle fall afternoon carries a meaningful UV load even when the sky looks completely gray.

There are two primary types of UV radiation that damage skin. UVB rays are the ones responsible for sunburn and vary somewhat with season, time of day, and cloud cover. UVA rays, however, are present at relatively constant intensity throughout the year—morning, noon, evening, summer, and winter alike. UVA penetrates clouds and glass and reaches deep into the dermis, driving photoaging and playing a significant role in melanoma development. Because UVA doesn't cause the visible burn signal that UVB does, Pacific Northwest residents often accumulate years of UVA damage without any awareness of it.

Washington state's melanoma diagnosis rates are not a statistical anomaly. The state has some of the highest melanoma rates in the Pacific Coast region, a pattern researchers attribute precisely to the false sense of security that comes with living in a historically "cloudy" climate. When people believe they are safe, they don't apply sunscreen, don't seek shade, and don't schedule annual skin checks—and cumulative UV damage builds silently over decades.

Why Pacific Northwest Residents Face Elevated Risk

Several factors combine to make the Pacific Northwest population disproportionately vulnerable to skin cancer beyond the cloud-cover misconception.

An intensely outdoor culture. Washingtonians hike, ski, kayak, mountain bike, and trail run at extraordinarily high rates. Recreational exposure on the water, in alpine terrain, and on open trails adds up to far more cumulative UV than a beach vacation ever would, partly because the duration of outdoor exposure on these activities is so long and people are not conditioned to think of them as "sun activities."

High-altitude UV exposure. Skiers and snowboarders at Crystal Mountain, Stevens Pass, and Snoqualmie Pass face a double threat: UV intensity increases approximately 4–5% for every 1,000 feet of elevation gained, and snow reflects up to 80% of UV back upward. A day on the slopes can expose skin to several times the UV dose of a day at sea level, often without sunscreen or protective clothing.

A predominantly fair-skinned population. Skin types I and II—those with light skin, light hair, and a tendency to burn rather than tan—carry 10 times the melanoma risk of darker skin types. Washington's demographic history means a large proportion of residents have this elevated baseline risk.

Underuse of sunscreen. National surveys show that sunscreen use is significantly lower in Pacific Northwest states than in Sun Belt states like Florida or Arizona. The weather-based reasoning is intuitive but medically incorrect: "It's not sunny enough to need sunscreen today" is a statement that contributes to thousands of preventable diagnoses each year.

The Three Types of Skin Cancer

Skin cancer is not a single disease. The three main types differ substantially in their appearance, behavior, and treatment approach.

Basal Cell Carcinoma (BCC) is the most common cancer of any kind in the United States, with approximately 3.6 million cases diagnosed each year. BCC arises from the basal cells in the deepest layer of the epidermis. It typically appears as a pearly or waxy bump, a flat flesh-colored or brown scar-like lesion, or a bleeding or scabbing sore that heals and returns. BCC rarely metastasizes but can cause significant local tissue destruction if left untreated. Because it grows slowly, it is highly curable when caught early.

Squamous Cell Carcinoma (SCC) accounts for roughly 1.8 million diagnoses per year in the U.S. SCC arises from the squamous cells in the outer layers of the skin and is more likely than BCC to spread to lymph nodes or distant organs, though metastasis is still relatively uncommon when the cancer is detected and treated early. SCC often presents as a firm red nodule, a flat lesion with a scaly, crusted surface, or a sore that does not heal.

Melanoma is the most dangerous form of skin cancer. While it accounts for only about 1% of skin cancers by volume, it causes the large majority of skin cancer deaths. The American Cancer Society estimated approximately 100,640 new melanoma diagnoses in the United States in 2024, with roughly 8,000 deaths annually. Melanoma develops in the melanocytes—the pigment-producing cells—and can arise in an existing mole or appear as a new dark spot. Its capacity to metastasize quickly to lymph nodes, lungs, liver, and brain makes early detection critical. Caught at stage I, melanoma has a 5-year survival rate above 98%. Caught at stage IV, that rate falls dramatically.

According to the American Academy of Dermatology (AAD), 1 in 5 Americans will develop skin cancer by the age of 70. That statistic applies in Seattle and Bellevue just as much as it does in Miami or Phoenix.

The ABCDE Rule: How to Spot a Suspicious Lesion

The ABCDE rule is a widely used clinical mnemonic for evaluating moles and spots for signs of melanoma. While it is not a substitute for a professional skin exam, understanding it helps patients know what to look for between annual check-ups.

• A — Asymmetry. A normal mole is symmetrical: if you draw a line through the middle, both halves look alike. A mole where one half doesn't match the other in shape is considered asymmetrical and warrants evaluation.
• B — Border. Benign moles have smooth, well-defined borders. Melanoma lesions often have irregular, ragged, notched, or blurred edges that are hard to define precisely.
• C — Color. A mole with multiple colors—varying shades of brown or black, or areas of red, white, or blue—is more concerning than one with a uniform, single color. Uneven pigmentation within a single lesion is a warning sign.
• D — Diameter. Melanomas are often larger than 6 millimeters (about the size of a pencil eraser) at the time of diagnosis. Any mole that reaches or exceeds this size should be examined, though smaller melanomas do exist and can be just as serious.
• E — Evolving. This may be the most important criterion. Any mole or skin lesion that is changing in size, shape, color, or texture—or that bleeds, itches, or crusts when it didn't before—should be evaluated promptly. Change is the hallmark of concern.

If a mole exhibits one or more of these features, schedule a professional skin examination as soon as possible. Do not wait until your next annual visit if you notice something changing.

Who Should Get a Skin Check—and How Often?

The AAD recommends that every adult undergo a full-body skin examination performed by a board-certified dermatologist at least once a year. This exam covers all skin surfaces, including areas that patients cannot easily see themselves: the scalp, back, backs of the ears, between the toes, and under the fingernails. A comprehensive skin check takes roughly 15–20 minutes and is often covered by insurance.

Certain patients should be seen more frequently—every 3 to 6 months in some cases. Higher-frequency monitoring is recommended for individuals with:

• A personal history of skin cancer (any type)
• A first-degree relative with melanoma
• Fifty or more moles, or any atypical (dysplastic) nevi
• A history of significant sunburns, particularly blistering burns in childhood or adolescence
• Immunosuppression (organ transplant recipients, patients on certain medications)
• Occupational or recreational outdoor exposure at high levels
• A history of tanning bed use

Younger patients sometimes assume skin cancer is a disease of old age and skip skin checks accordingly. In reality, melanoma is one of the most common cancers in adults under 30, and the Pacific Northwest's active outdoor culture means young residents may be accumulating significant UV exposure from an early age. We encourage patients of all ages, including teenagers with risk factors, to establish care with a dermatologist.

Treatment Options at Dermatology of Seattle

When skin cancer is diagnosed, treatment depends on the type, size, location, and stage of the cancer. Dermatology of Seattle offers a comprehensive range of treatment modalities, including an on-site surgical center that allows most procedures to be completed in one convenient location at our Burien or Bellevue offices.

Mohs Micrographic Surgery is the gold standard treatment for BCC and many SCC cases, particularly when they appear on the face, ears, hands, or other cosmetically or functionally sensitive areas. In Mohs surgery, the surgeon removes the tumor one thin layer at a time and examines each layer under the microscope immediately. The process continues until no cancer cells remain. This technique achieves a cure rate of up to 98% for primary BCC—the highest of any treatment for skin cancer—while sparing the maximum amount of healthy surrounding tissue. Learn more about Mohs surgery at our clinic.

Brachytherapy uses controlled, localized radiation applied directly to the tumor site. It is an effective non-surgical option for patients who cannot undergo surgery or for cancers in locations where surgery carries a higher risk of functional impairment.

Surgical excision remains the standard first-line treatment for many skin cancers and melanomas. The tumor is removed with an appropriate margin of healthy tissue, and the margins are sent to pathology for confirmation. For melanoma, excision is performed with wider margins and may be accompanied by sentinel lymph node biopsy.

Systemic therapies, including targeted agents and immunotherapy, may be recommended for advanced melanoma in coordination with oncology. Our team will guide you through all available options and refer appropriately when needed. Visit our skin cancer services page for a full overview.

Prevention: What You Can Do Starting Today

The good news about skin cancer is that it is largely preventable with consistent protective habits. These recommendations apply year-round in the Pacific Northwest, not just on sunny summer days.

• Use SPF 30 or higher sunscreen every day. Apply it every morning as the last step in your skincare routine, regardless of the weather forecast. Choose a broad-spectrum formula that blocks both UVA and UVB rays.
• Reapply every two hours when outdoors. Sunscreen degrades with time, sweat, and water exposure. A single morning application is not sufficient for a full day of outdoor activity. Water-resistant formulas provide some extended protection but still require reapplication.
• Wear UPF-rated clothing. Ultraviolet Protection Factor (UPF) clothing is specifically tested for UV blocking performance. A UPF 50 garment blocks 98% of UV radiation—far more reliably than ordinary fabric. Pair with a wide-brimmed hat and UV-blocking sunglasses.
• Avoid peak UV hours. UV radiation is most intense between 10 a.m. and 4 p.m. When hiking, skiing, or spending time outdoors, seek shade during this window whenever possible or be especially diligent about sun protection.
• Never use tanning beds. Tanning beds emit concentrated UVA radiation and have been classified as a Group 1 carcinogen by the World Health Organization. Studies have found that using a tanning bed even once before age 35 increases the risk of melanoma by 75%. There is no safe amount of tanning bed use.
• Perform monthly self-exams. Familiarity with your own skin is one of the best early detection tools available. Examine your entire body monthly using a full-length mirror and a hand mirror for hard-to-see areas, and note any new or changing spots.

The Bottom Line for Pacific Northwest Residents

Seattle's reputation for gray, rainy weather does not translate into protection from skin cancer. Up to 80% of UV radiation penetrates cloud cover. UVA rays are present year-round. Washington state's outdoor culture, high-altitude recreation, and fair-skinned population create a convergence of risk factors that make regular skin monitoring not a luxury but a genuine medical necessity.

With 1 in 5 Americans expected to develop skin cancer by age 70, and melanoma causing approximately 8,000 deaths every year in the U.S., the stakes are too high to rely on weather-based assumptions. Annual skin checks with a board-certified dermatologist, combined with daily sunscreen and protective habits, can make a life-changing difference—and at Dermatology of Seattle, that's exactly the kind of preventive care we're here to provide.