Many people think sunscreen is only necessary on hot, sunny summer days. The truth is, your skin is exposed to ultraviolet (UV) radiation every day of the year, even when it’s cloudy, cool outside, or you’re spending time indoors near windows.
Over time, UV exposure can lead to sunburn, premature skin aging, and an increased risk of skin cancer. That’s why dermatologists and primary care providers recommend making daily sun protection an important part of your daily routine, not just something you add at the beach.
Why UV exposure happens more often than you think
Most people associate sun damage with obvious sunburns, but UV radiation can affect your skin even when you don’t feel it happening.
UV rays are present all day
To implement a good strategy of UV protection, first examine the conditions that influence UV exposure. Understand timing: UVA vs UVB during the day. There are two main types of UV radiation that affect your skin:
- UVB rays are strongest between 10 a.m. and 4 p.m. These are what is primarily responsible for sunburn!
- UVA is relatively consistent throughout daylight hours and contributes to premature aging and long-term skin damage.
Windows don’t fully protect your skin
Glass is not a full shield. Standard window glass blocks most UVB but can allow UVA through—so you can get cumulative damage while driving or sitting near windows.
Cloudy days still count
Clouds are not protective. Up to 80% of total UV radiation penetrates through clouds. You can get burned on a cloudy day as well. Scattered clouds can act like magnifying glasses, reflecting and scattering rays to increase UV levels.
Higher elevation means more UV exposure
The higher you go the less UV light is filtered out by the atmosphere. UV radiation increases by about 10–12% for every 3,300 ft of elevation gain under clear skies. This is especially relevant during daytime flights when seated by a window.
This ongoing exposure contributes to cumulative sun damage and helps explain why there’s no such thing as a healthy tan.
Sunscreen is important, but it’s not the only form of sun protection
When thinking about sun protection, think beyond sunscreen alone. Seeking shade, wearing sun-protective clothing, sunglasses, and wide-brimmed hats, and limiting time outdoors during peak UV hours are all important ways to reduce cumulative UV exposure.
How to choose the right sunscreen
When choosing a sunscreen, look for one that provides broad-spectrum protection, has an SPF of 30 or higher, and is water resistant for either 40 or 80 minutes. These features help protect against both UVA and UVB radiation and provide more reliable protection during outdoor activities.
Let’s break down what these recommendations mean:
- Broad-spectrum sunscreens protect against both UVA and UVB radiation, giving you more complete protection during daily activities and outdoor recreation.
- SPF stands for Sun Protection Factor. It measures how effectively a sunscreen protects against UVB rays, which are the rays responsible for sunburn.
Think of sunburn like this: Your skin can only tolerate a certain amount of UV exposure before it starts to burn. Sunscreen doesn’t make you immune to sunburn. Instead, it slows the rate at which UV exposure damages your skin, giving it more time before redness appears.
Not sure which kind of sunscreen to choose? Read our guide on mineral vs. chemical sunscreen to learn which option may be best for your family.
What does SPF actually mean?
A higher SPF gives your skin more time before it reaches the point of burning, but no sunscreen blocks 100% of UV radiation. That’s why reapplication and other sun protection habits are still important.
It’s also important to remember that SPF ratings only measure protection against UVB rays. In the United States, there is currently no standardized rating system for UVA protection, which is why choosing a broad-spectrum sunscreen matters.
How much sunscreen do I need to apply?
The FDA recommends applying approximately one ounce (about a shot glass full) for the average adult body and about 1/10 ounce (roughly 3mL) to cover the face and neck.
Don’t forget to reapply every two hours outdoors and reapply sooner after swimming or sweating heavily!
Daily sunscreen use is one of the simplest ways to protect your skin from premature skin aging and skin cancer.
Whether it’s sunny, cloudy, hot, or cold, UV exposure happens every day. Making sunscreen part of your daily routine can help protect your skin for years to come.