Know your UV Index

What is the UV Index?

The UV index, an international standard measurement, is a scale designed to inform of how strong the ultraviolet (UV) radiation from the sun will be in a particular place on a particular day. The scale is primarily used for daily forecasts to encourage the general public to make informed choices in the amount of time spent in the sun, the proper sunscreen protection and UV protective clothing to wear.

Its purpose is to help people to effectively protect themselves from UV light, of which excessive exposure causes sunburns, eye damage such as cataracts, skin aging, and skin cancer. Public-health organizations recommend that people protect themselves (for example, by applying sunscreen to the skin and wearing a hat or UV protective clothing) when the UV index is 3 or higher; see the table below for complete recommendations.(Wikipedia)



UV Index forecast map

The forecast map shows contour lines of predicted UV Index values during the solar noon hour. The map is created daily from National Weather Service forecast data.


UV Index forecast map
UV Index forecast map

Recommendations for protection when the day's predicted UV index is at various values are:

UV Index Description Media Graphic Color Recommended Protection
0–2 No danger to the average person Green Wear on bright days; use sunscreen if there is snow on the ground, which reflects UV radiation, or if you have particularly fair skin.
3–5 Little risk of harm from unprotected sun exposure Yellow Wear sunglasses and use sunscreen, cover the body with clothing and a hat, and seek shade around midday when the sun is most intense.
6–7 High risk of harm from unprotected sun exposure Orange Wear sunglasses and use sunscreen having 15 or higher, cover the body with sun protective clothing and a wide-brim hat, and reduce time in the sun from two hours before to three hours after solar noon (roughly 11:00 AM to 4:00 PM during summer in zones that observe daylight saving time.
8–10 Very high risk of harm from unprotected sun exposure Red Wear sunscreen, a shirt, sunglasses, and a hat. Do not stay out in the sun for too long.
11+ Extreme risk of harm from unprotected sun exposure Violet Take all precautions, including: wear sunglasses and use sunscreen, cover the body with a long-sleeve shirt and trousers, wear a very broad hat, and avoid the sun from two hours before to three hours after solar noon.