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Wearing sunscreen is one of the simplest habits you can adopt for your long-term health — and yet a surprising amount of bad advice still gets passed around. Here are six of the most common sun safety myths, and what the evidence actually says.
Myth #1—I don’t need sunscreen on a cloudy day.
The truth: Up to 80% of UV rays pass right through clouds. An overcast sky may dial down the brightness and heat, but does very little to block the radiation that causes skin damage. In fact, clouds may even increase UV radiation. UVA rays — the ones responsible for premature aging and long-term damage — maintain consistent intensity year-round, rain or shine, and even penetrate glass. The habit worth building: apply sunscreen every day, not just when the sun is out.
Myth #2—Once I apply sunscreen in the morning, I’m covered for the day.
The truth: Sunscreen breaks down with sun exposure, sweat, and water. Applying once in the morning provides good initial protection, but it won’t last all day — especially if you’re spending time outdoors. Reapply every two hours, or immediately after swimming or toweling off, even if your label says “water resistant.” And if you use a spray, rub it in — a light mist rarely provides enough coverage.
This video from the American Academy of Dermatology walks you through how to best apply sunscreen.
Myth #3—A base tan will protect me.
The truth: A tan isn’t protection — it’s evidence of damage. Your body produces melanin as a defense response to UV radiation, but it’s not very effective. According to the CDC, a ‘base tan’ offers roughly the UV protection of SPF 3. If you want the glow without the risk, self-tanner is a safe alternative — just know it provides zero UV protection on its own.
Myth #4—SPF 100 is twice as good as SPF 50.
The truth: SPF doesn’t work on a linear scale. Here’s the actual breakdown:
- SPF 30 filters about 97% of UVB rays
- SPF 50 filters about 98%
- SPF 100 filters about 99%
That’s a 1% difference — not double the protection. A well-applied SPF 30 will outperform a quickly-swiped-on SPF 100 every time. For most people, SPF 30–50 is the practical sweet spot. Just make sure it says broad-spectrum on the label — that means it protects against both UVA and UVB radiation, not just the rays that cause sunburn. Learn more about how SPF is measured in Why sunscreen works.
Myth #5—I need lots of sun exposure to get enough vitamin D.
The truth: You don’t need as much as you think — and unprotected sun exposure isn’t the safest way to get it. Most people get adequate vitamin D from just a few minutes of daily incidental exposure. In Minnesota, the sun’s angle from fall through early spring means UV levels are often too low to trigger meaningful vitamin D production anyway, no matter how much time you spend outside. Diet and supplements are a safer, more reliable route. We explored this in depth in Vitamin D – sunshine or supplements?
Myth #6—The sun is strongest when it’s hottest.
The truth: UV intensity and air temperature aren’t the same thing. UV peaks around solar noon — roughly 10 a.m. to 4 p.m. — when the sun is highest in the sky and its rays travel the shortest distance through the atmosphere. Temperature peaks in the mid-to-late afternoon, after the ground has absorbed heat throughout the day. That cool morning on the water can carry just as much UV risk as the hottest part of the afternoon. Check the UV Index for Kanabec County in your weather app — it’s a far better guide than how warm it feels.
Keep it simple
Good sun protection doesn’t have to be complicated: apply SPF 30+ every day, reapply every two hours when you’re outdoors, and pair it with a hat and shade during peak hours. For a full guide on choosing and applying the right product, check out our Summer sunscreen guide.
And if you notice a new or changing mole, a spot that bleeds, or anything that looks unusual, don’t wait — schedule a visit with your Welia Health provider. Skin cancer caught early is almost always treatable.
Call Welia Health at 320.679.1313 or log into MyChart to schedule an appointment.
