UV Safe TanWhat Is the UV Index? The 0 to 11+ Scale Explained
Short answer: the UV index is a number, usually from 0 to 11 or higher, that tells you how strong the sun's burning ultraviolet radiation is right now. One point equals 25 milliwatts per square metre of skin-weighted UV. At 3 or above, the World Health Organization recommends sun protection. At 8 or above, unprotected very fair skin can burn in under 20 minutes.
The UV index scale
| UV index | Level | What to do |
|---|---|---|
| 0 to 2 | Low | Minimal risk for most people. Sunglasses on bright days. |
| 3 to 5 | Moderate | Seek shade around midday. Hat, sunglasses and SPF 30 or higher. |
| 6 to 7 | High | Reduce time in the sun between 10 AM and 4 PM. Full protection. |
| 8 to 10 | Very high | Extra care. Unprotected skin burns quickly. Avoid midday sun. |
| 11+ | Extreme | Avoid the sun around midday. Cover up and reapply sunscreen often. |
What makes the UV index go up
- Time of day. UV peaks around solar noon, usually between noon and 1 PM, or 1 and 2 PM during daylight saving time.
- Season and latitude. The closer the sun is to directly overhead, the higher the index. Tropical cities can reach 11 or more most of the year.
- Altitude. UV rises roughly 10 percent for every 1,000 metres you climb.
- Clouds. Thin or broken cloud lets most UV through, and can even increase it for short periods. Cool, cloudy days still burn.
- Reflection. Snow reflects up to 80 percent of UV, sand about 15 percent and water about 10 percent, adding to the dose you get from above.
Temperature is not UV
Heat comes from infrared light, burning comes from ultraviolet. A cool, breezy spring day at high altitude can carry a higher UV index than a hot, hazy summer afternoon. Always check the number, not the thermometer.
How to check the UV index where you are
Most weather apps bury UV below the forecast. UV Safe Tan puts it front and centre: a live gauge for your exact location, the hour-by-hour curve for the rest of the day, a 7-day outlook, and a Home Screen widget so you can see the number without opening anything.
UV Safe Tan is coming soon
Live UV index for where you are, a burn timer set by your skin type and SPF, reapply reminders, a tan timer that stops before you burn, and Home Screen widgets. For iPhone and iPad.
Coming soon to theApp StoreMore guides
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A burn time chart by skin type and UV index, plus how much SPF really buys you.
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Short sessions, the right hours and a clear stopping point, minus the myths.
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