The UV Index, or ultraviolet index, is an international scale that measures the level of ultraviolet radiation reaching the ground. The scale starts at zero, and the higher it goes, the less time to takes for damage to occur to skin and eyes, so people of every skin type are effected.
Here in southeast Michigan, nine is usually the highest UV number we see, but closer to the equator, the number can soar to 12 or even higher.
The UV index isn't directly related to temperatures, but the sun's rays are stronger closer to the Summer Solstice in June, so UV numbers are higher in spring and summer.
Clouds thick enough to bring rain can block some UV rays, but clouds farther from the ground let most of that radiation through.
We include the UV index in our weather reports during the warmer times of year so you can be sun safe: too much sun can lead to skin cancer and cataracts.
Use 30 or higher SPF sunscreen and reapply often.
Enjoy the shade, especially when the sun is strongest between 10 a.m. and 4 p.m.
Protective clothing also helps, like long-sleeved shirts, hats and sunglasses.