The UV Index: How to Actually Use It

The UV Index (UVI) is an international standard that measures the intensity of UV radiation reaching the Earth's surface on a given day. It was developed to give people a simple, actionable number — but most people do not know what each level actually means for their skin or when they need to take action.

• UV Index 0–2 (Low): minimal risk for most people. SPF still recommended for long outdoor time.
• UV Index 3–5 (Moderate): unprotected skin begins to burn in 30–45 minutes for fair skin. SPF 30+ recommended.
• UV Index 6–7 (High): burn time drops to 15–25 minutes. Seek shade during midday hours.
• UV Index 8–10 (Very High): burn in under 15 minutes. SPF 50+, protective clothing, and shade are important.
• UV Index 11+ (Extreme): common in summer at high altitudes and near the equator. Take all precautions — burn in minutes.
• UV peaks between 10am–2pm regardless of season. It is also highest at altitude (increases ~10% per 1,000m) and near reflective surfaces — snow reflects up to 80% of UV, sand ~15–25%, water ~10%.