The highest ultraviolet (UV) index ever recorded was 43.3, measured on December 29, 2003, at the Licancabur volcano in Bolivia. This extremely high UV index represents an extreme risk of harm from unprotected sun exposure and is far beyond the typical UV index scale that runs from 0 to 11+ used for daily forecasts. Such extreme UV levels are usually found in high-altitude tropical regions, such as the Altiplano in South America, where UV indexes routinely exceed 20 during summer months
. In general, the UV index scale is designed as follows:
- 0-2: Low risk
- 3-5: Moderate risk
- 6-7: High risk
- 8-10: Very high risk
- 11+: Extreme risk
Values above 11 are considered extreme, but the record of 43.3 is exceptional and not typical for most locations on Earth
. Regions known for very high UV indexes include high-altitude areas in South America, parts of Sub-Saharan Africa, Australia, and equatorial mountain elevations in Kenya, Indonesia, and Ecuador
