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.
UV Index information are available on EPA Sun Safety web site