The UV Alert is based statistically upon a locale's daily climatological mean UV Index and its historical variability for that day (standard deviation). Initially, for a locale to qualify to be within a UV Alert region the UV Index must be "High" or 6 and above. If the UV Index is greater than the locale's climatological mean plus one half standard deviation it is considered to be 'above normal'. If the UV Index is greater than the locale's climatological mean plus one standard deviations it is considered to be 'well above normal' and placed within the UV Alert region. Additional UV Index information are available on EPA Sun Safety web site |