How do you know if the UV rays are strong or not?
Ultraviolet (UV) radiation is the invisible killer that you can't see or smell. UV radiation can be high even in cool, overcast weather. This means that you can't rely on clear skies or high temperatures to determine when you need to protect yourself from the sun. You need to start protecting yourself from a UV index of 3 (on a scale of 12).
The UV index is communicated daily by weather forecasting websites.