weather term
UV Index
A scale, typically 0 to 11+, describing the strength of ultraviolet radiation from the sun and the sunburn risk it poses.
The UV index rises with the sun's height in the sky, so it typically peaks around midday and is higher in summer, at high altitude, and closer to the equator. A reading of 3 to 5 is considered moderate and calls for some sun protection, while 8 and above is very high and can cause sunburn in under 15 minutes on unprotected skin, regardless of how hot or cold the air temperature feels.