Conditions on this page are recalculated from the latest forecast every time it is opened, for the current date in the location's own time zone.
A UV index of 6 or higher is considered high risk and requires sun protection. At UV index 8–10 (very high), unprotected skin can burn in 15–25 minutes. At UV index 11+ (extreme), damage can occur in under 10 minutes. Always wear SPF 30+ sunscreen, protective clothing, and sunglasses when the UV index exceeds 3. Dermatologists recommend wearing sunscreen whenever the UV index is 3 or above. At UV 1–2, minimal protection is needed for average skin types. However, people with fair skin, a history of skin cancer, or high altitude exposure should consider sunscreen even at lower UV levels. Yes. Up to 80% of UV radiation penetrates thin cloud cover. Overcast skies can create a false sense of security, leading to longer unprotected exposure. Always check the UV index regardless of cloud conditions, especially during summer months. UV radiation peaks between 10 AM and 4 PM, with the absolute highest levels typically occurring between 11 AM and 1 PM solar time. The sun's angle is most direct during these hours, allowing maximum UV penetration through the atmosphere. Yes, UV intensity increases approximately 6–8% for every 1,000 feet (300 meters) of elevation gain. At 10,000 feet, UV radiation is roughly 50% stronger than at sea level. Mountain hikers, skiers, and high-altitude travelers face significantly elevated UV exposure. Complete guide to the UV index scale from 0–11+. Learn what UV levels require sunscreen, when sun exposure becomes dangerous, and how to protect yourself at every level. The UV index is a straightforward scale from 0 to 11+, yet most people ignore it until they are already sunburned. Understanding what each level means — and how quickly damage occurs — transforms this simple number into one of the most important weather metrics you can check. The UV index is an international standard measurement of ultraviolet radiation intensity at the Earth's surface. Developed by the World Health Organization (WHO) and adopted globally, it provides a single number that indicates the strength of skin-damaging UV rays at a specific time and location. The scale starts at 0 (nighttime, no UV) and typically maxes out around 11–12 in most inhabited regions. However, extreme locations — high altitude equatorial zones, reflective snow surfaces, or areas with ozone depletion — can see values exceeding 14. The higher the number, the faster unprotected skin sustains damage. *Approximate burn time for fair, unprotected skin. Darker skin types have longer burn times but still sustain UV damage. At UV index 0–2, the sun's rays are weak enough that most people can safely spend extended time outdoors without sunscreen. This typically occurs during early morning, late afternoon, winter months at high latitudes, or heavily overcast conditions. Even at low UV, cumulative exposure matters. If you spend all day outdoors at UV index 2 — say, during a winter hike — total exposure adds up. People with very fair skin or a history of skin cancer should still consider protection during prolonged outdoor periods at any UV level. This is the range where most spring and fall midday readings fall in temperate climates. Unprotected fair skin can burn within 30–45 minutes. Apply SPF 30 or higher sunscreen, wear a hat and sunglasses, and seek shade during peak hours if spending extended time outdoors. Many people underestimate moderate UV because it does not "feel" intense. However, UV radiation is invisible — you cannot feel it the way you feel infrared heat. Sunburn develops hours after the damage occurs, making real-time perception unreliable. At UV 6–7, common during summer in most of the continental United States and year-round in tropical regions, unprotected skin can burn in 15–25 minutes. This is the threshold where dermatologists strongly recommend comprehensive sun protection for everyone, regardless of skin tone. UV index 8–10 occurs during peak summer in southern states, at high altitudes, near the equator, and on reflective surfaces like sand, water, and snow. Burn times drop to 10–20 minutes for unprotected fair skin. At this level, even brief unprotected exposure during errands or lunch breaks can cause damage. Make it as routine as checking temperature. Use Snap Weather to see UV alongside all other conditions.
Scores are capped by dealbreakers — heavy rain, dangerous wind, thick fog or hazardous UV pull a day down no matter how pleasant the rest of the numbers look. Forecast data is Open-Meteo; solar and lunar values are computed for Uv Index Guide's own coordinates and time zone. Full details on the methodology page.