Why UV Protection is Crucial Even on Cloudy Days


Photo by Andrea Piacquadio

Many people assume that UV radiation is only a concern on sunny days when the sun is shining brightly. However, the truth is that UV rays can penetrate clouds and reach the Earth’s surface even on overcast days.

Understanding UV Radiation

UV radiation is a form of electromagnetic radiation emitted by the sun. It consists of UVA, UVB, and UVC rays, with UVA and UVB being the most relevant to human health. These rays can penetrate the Earth’s atmosphere and cause various health issues, including sunburn, premature aging, and an increased risk of skin cancer.

UV Radiation on Cloudy Days

While clouds may block some visible sunlight, they often provide little to no protection against UV radiation. Up to 80% of UV rays can penetrate cloud cover, depending on the cloud’s thickness and composition. This means that even on overcast days when the sun may not be visible, UV radiation can still reach the Earth’s surface and pose a risk to our health.

Why UV Protection is Crucial on Cloudy Days

  • Skin Damage: UV radiation can cause immediate damage to the skin, leading to sunburn and irritation, even on cloudy days. Prolonged exposure to UV rays without protection can also increase the risk of skin cancer and premature aging.
  • Eye Damage: UV radiation can penetrate the eyes’ delicate structures, leading to short-term discomfort and long-term eye conditions.
  • Cumulative Effects: UV damage accumulates over time, meaning that even brief exposure on cloudy days can contribute to long-term health issues. Consistent UV protection is essential for minimizing the risk of sun-related damage and maintaining overall health.


Photo by Shvets Anna

Tips for UV Protection on Cloudy Days

  • Wear Sunscreen: Apply a broad-spectrum sunscreen with SPF 30 or higher to all exposed skin, including your face, neck, and hands, even on cloudy days.
  • Use Sunglasses: Wear sunglasses with UV protection to shield your eyes from harmful UV rays, reducing the risk of eye damage and discomfort. You can also add polarized lenses to cut down on glare.
  • Cover Up: Wear lightweight, long-sleeved clothing, hats, and other protective accessories to minimize skin exposure to UV radiation.
  • Stay Hydrated: Drink plenty of water to stay hydrated, as proper hydration can help support overall skin health and resilience against UV damage.
  • Seek Shade: Whenever possible, seek shade or create your own using umbrellas, canopies, or trees to reduce direct exposure to UV radiation.


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Cloudy days may give a false sense of security when it comes to UV protection, but the reality is that UV radiation can still reach the Earth’s surface and pose health risks. By understanding the importance of UV protection and wearing sunglasses regardless of the weather conditions, we can protect ourselves from sun-related damage and enjoy healthier, happier lives.

Avatar of Dr. Steven Liem

Dr. Steven Liem

Dr. Steven Liem, O.D., F.A.A.O. is an optometrist based in Pasadena, California. After obtaining his doctorate from UC Berkeley’s School of Optometry, he completed his residency in Pediatrics, Vision Therapy & Rehabilitation and became a Fellow of the American Academy of Optometry. When he isn’t busy streaming or making Youtube videos about video games, Dr. Liem aims to broaden accessibility to vision health through his involvement in optometric industry and tech.