The UV index is an international standard measurement of the strength of UV radiation from the sun at a particular time and place. Its purpose is to help people protect themselves from the effects of UV light, in particular to avoid sunburn.

The strength of UV light mainly depends on the altitude of the sun (hence time of day, season and geographic latitude) and geographic altitude, but also on cloud cover. Additional factors are skin-type and prior exposure to the sun. The guidelines given on WeatherPro are based on fair, sensitive skin.
The following guidelines can be used:

• 0-1: No danger, sunburn improbable, no precautions necessary. Special measures: None – you can stay outside without risk.
• 2-4: Small risk of sunburn after 30 minutes, precautions necessary. Special measures: Seek shade around midday, use sunscreen, keep your body covered and use a hat.
• 5-7: High risk of skin damage, sunburn after 20 minutes, precautions necessary. Special measures: Seek shade around midday, use sunscreen, keep your body covered and use a hat.
• 8+: Very high risk of skin damage, sunburn in less than 20 minutes, precautions strictly necessary. Special measures: Do not stay in the sun around midday. Look for shade, use sunscreen, keep your body covered and use a hat.