How to Read the UV Index: What Each Number Means and When to Cover Up
Turn that abstract weather-app number into a daily decision: at a UV Index of 3 you need protection, and at 11+ skin can burn in minutes.
The EPA UV Index runs from 1 (Low) to 11+ (Extreme); protection is needed at a reading of 3 or higher, and at 11+ unprotected skin can burn within minutes.
The EPA frames the UV Index as a daily forecast tool, advising that once readings reach 3 or higher people should seek shade, cover up, and apply sunscreen — the same way you'd plan around a rain forecast.
Questions we get a lot
At what UV Index do I need sunscreen?
Protection is recommended once the UV Index reaches 3 or higher, according to the EPA's scale. At those levels the agency advises seeking shade, wearing protective clothing and a hat, and applying broad-spectrum sunscreen. Below 3, the risk for the average person is low, though sensitive skin can still benefit from protection.
What does a UV Index of 11 or higher mean?
A reading of 11 or above is rated Extreme on the EPA scale, the highest category. At that level, unprotected skin can burn in just minutes, so the EPA recommends avoiding the sun during midday hours and using every protective measure if you must be outside. Take it as a signal to stay in shade as much as possible.
What is the shadow rule?
The shadow rule is a quick, no-tech way to gauge UV intensity: if your shadow is shorter than you are tall, the sun is high and UV is strong, so protection is important. A long shadow means the sun is lower and UV is weaker. It's a handy check when you don't have a UV forecast on hand.
r/SkincareAddiction: 'My weather app shows a UV index number every morning but I have no idea what counts as high. At what point do I actually need to slather on SPF?'