Cold weather does not mean low UV

The UV index measures ultraviolet radiation. Higher values mean greater potential for skin and eye damage, with less time needed for harm to occur. Temperature and UV belong in the same weather forecast, but they are not interchangeable just because they share a screen. Local air temperature also changes with elevation, nearby water, wind and cloud cover.13

A clear winter morning still brings UV exposure. Winter sports can increase sunburn risk because higher altitude and UV reflected from snow add to exposure. A cold day is not a reason to set sunscreen aside when heading outdoors.2

What should you do at each UV index?

UV indexWhat to do outdoors
0 to 2Under normal circumstances, additional sun protection is not needed.
3 to 7Seek shade around midday. Use sunscreen, protective clothing, a wide brimmed hat and sunglasses.
8 and aboveAvoid being outside around midday where possible. Use shade, protective clothing, a hat, sunglasses and sunscreen.
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These bands change the precautions you take, rather than giving you a different sunscreen number for every forecast. SPF 30 or higher is a practical choice for exposed skin throughout the year. At very high UV levels, add stricter shade and time outdoors decisions instead of relying on sunscreen alone.12

Check the time as well as the number

UV levels change throughout the day. A daily UV forecast usually reports the maximum, which occurs during the four hours around solar noon. Solar noon can fall between noon and 2 p.m., depending on location and daylight saving time. If the forecast provides sun protection times, use those to plan when protection is needed rather than treating the daily maximum as an hourly reading.1

Your shadow can also give a rough clue about UV exposure, making it one of the few weather tools that requires neither a battery nor an account. A shadow shorter than you indicates higher UV exposure: seek shade and protect your skin and eyes. A taller shadow, usually in early morning or late afternoon, suggests lower exposure.4

How to protect exposed skin

  1. 1Check the UV forecast for your location before going outdoors, including any listed sun protection times.
  2. 2Cover skin with protective clothing and use a wide brimmed hat and sunglasses with UV protection. Look for a UPF label on clothing.
  3. 3Apply broad spectrum, water resistant SPF 30 or higher to uncovered skin at least 15 minutes before exposure. Include ears, nose, lips, the back of the neck, and exposed hands and feet.
  4. 4Reapply at least every two hours, or after swimming or sweating.
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Sun protection applies across skin types and tones. Take particular care if you have a personal or family history of skin cancer.2

Where this answer comes from

  1. 1Radiation: The ultraviolet (UV) indexwho.int
  2. 2Why you need sun protection in the winteraad.org
  3. 3Weather tools: frequently asked questionscanada.ca
  4. 4UV Index Scaleepa.gov