Preventing sunburn comes down to three things: limiting your exposure during peak hours, covering your skin, and using sunscreen correctly. Most sunburns happen not because people skip protection entirely, but because they apply too little sunscreen, forget to reapply, or underestimate how strong the UV radiation is on a given day. Here’s how to get each layer of protection right.
Check the UV Index Before You Go Out
The UV Index is a 1 to 11+ scale that tells you how intense the sun’s radiation is at your location on a given day. Most weather apps display it. At 1 or 2, you can be outside with minimal protection. At 3 to 7, you need sunscreen, shade, and protective clothing. At 8 and above, unprotected skin can burn in minutes, and you should limit time outdoors during midday hours.
The sun is strongest between late morning and mid-afternoon, roughly 10 a.m. to 2 p.m. A useful trick from the EPA: if your shadow is shorter than you are, the UV radiation is intense enough to warrant extra caution. This applies even on partly cloudy days, since UV rays penetrate cloud cover.
Wear Clothing That Actually Blocks UV
Clothing is more reliable than sunscreen because it doesn’t wear off, wash away, or get applied unevenly. But not all fabric offers the same protection. A sheer white t-shirt lets a surprising amount of UV through, while darker, tightly woven fabrics block much more.
If you want a guarantee, look for clothing with a UPF (Ultraviolet Protection Factor) rating. UPF 15 blocks about 93% of UV radiation. UPF 30 blocks roughly 97%. UPF 50+ blocks 98%. For hats, choose a wide brim that shades your face, ears, and neck. Baseball caps leave the ears and back of the neck exposed, which are common burn spots. Sunglasses with UV protection cover the skin around your eyes and reduce your risk of eye damage.
Choose the Right Sunscreen
Sunscreen needs to block two types of ultraviolet radiation. UVB rays are the primary cause of sunburn. UVA rays penetrate deeper into the skin and contribute to aging and skin cancer, but they also play a role in burning. A product labeled “broad spectrum” has passed an FDA test confirming it filters both UVA and UVB, so always look for those words on the bottle.
SPF 30 is a good baseline for most people. It filters about 97% of UVB rays. SPF 50 gets you to roughly 98%. The jump from 30 to 50 is small, and no sunscreen blocks 100%. What matters more than a sky-high SPF number is applying enough and reapplying on time.
You’ll find two main types of sunscreen. Mineral sunscreens use zinc oxide or titanium dioxide to sit on the skin’s surface and physically reflect UV rays away. Chemical sunscreens absorb UV rays and convert them to heat, which your skin releases. Both work. Mineral formulas tend to be better tolerated by sensitive skin and are the preferred choice for young children. Chemical sunscreens often feel lighter and blend more easily into darker skin tones without leaving a white cast.
Apply Enough, and Reapply on Schedule
Most people apply about a quarter to a half of the sunscreen they actually need, which dramatically reduces the protection they get. For full-body coverage, use about one ounce per application. That’s roughly a shot glass full. For just your face and neck, a nickel-sized amount is a good target. Apply it 15 to 20 minutes before going outside so it has time to bond with your skin.
Reapply every two hours when you’re outdoors. That timeline shortens significantly if you’re swimming or sweating. Water can weaken and wash off sunscreen within 45 minutes to an hour, even with water-resistant formulas. Toweling off removes it too. If you’ve been in the pool or ocean, reapply as soon as you’re dry. Heavy sweating from exercise or yard work has a similar effect, so plan to reapply within an hour during vigorous activity.
One more detail people overlook: sunscreen expires. The FDA requires it to maintain its original strength for at least three years. If your bottle doesn’t have an expiration date, write the purchase date on it and toss it after three years. Storing sunscreen in a hot car or leaving it baking in the sun at the beach also degrades its effectiveness faster.
Watch for Reflected UV
You can burn even in the shade if UV radiation is bouncing off nearby surfaces. Fresh snow reflects 85% of UV rays, which is why skiers burn so easily at altitude. Dry sand reflects about 17%, enough to burn the underside of your chin, your ears, and other spots you might not think to protect. Water reflects a smaller percentage at most angles but still adds to your total exposure, especially on a boat where light hits you from multiple directions.
Altitude matters too. UV intensity increases roughly 10 to 12% for every 1,000 meters of elevation gain. A hike at 8,000 feet demands more protection than a walk at sea level, even if the temperature feels cool.
Your Skin Type Affects Your Risk
People with very fair skin, light eyes, and red or blonde hair burn the fastest, sometimes in under 10 minutes of strong midday sun. The Fitzpatrick scale classifies skin into six types: Type I always burns and never tans, Type II usually burns with minimal tanning, and Type III occasionally burns but generally tans. Types IV through VI burn rarely to never and tan easily.
Having darker skin does not mean you can skip sun protection. While melanin provides some natural UV filtering, UVA radiation still penetrates and causes cumulative damage regardless of skin tone. Skin cancers in darker-skinned individuals are often diagnosed later because there’s a false sense of immunity. Everyone benefits from the basics: shade, clothing, and sunscreen on exposed skin.
Protecting Babies and Young Children
Babies younger than six months should be kept out of direct sunlight entirely. Their skin is thinner and more vulnerable to both UV damage and potential reactions from sunscreen ingredients. The FDA and the American Academy of Pediatrics recommend shade as the primary protection for newborns: stroller canopies, pop-up tents, trees, or beach umbrellas.
Dress infants in lightweight long-sleeve shirts and long pants with tight weaves. A quick test: hold the fabric up to your hand. If you can see through it, it won’t provide enough protection. Hats should have a full brim that covers the face, neck, and ears. If you need to use sunscreen on an infant under six months, check with your pediatrician first, as babies are more prone to skin reactions from sunscreen ingredients. For children older than six months, apply sunscreen to any skin that clothing doesn’t cover, and reapply just as you would for yourself.
Putting It All Together
The most effective sun protection is layered. Start by checking the UV Index and planning outdoor time outside peak hours when possible. Wear UPF-rated or tightly woven clothing, a wide-brimmed hat, and UV-blocking sunglasses. Apply a full ounce of broad-spectrum SPF 30 or higher sunscreen to exposed skin, and set a timer to reapply every two hours, or sooner if you’re swimming or sweating. Account for reflected UV from sand, water, or snow. No single strategy is perfect on its own, but combining them makes sunburn genuinely difficult to get.