Answer: uvindex

AnswerCrossword Clue
UVINDEXScale used in summer weather forecasts
UVINDEXSunburn-related meas.
UVINDEXMeasure discussed on the EPA's SunWise web page
UVINDEXMeasure of burning potential
UVINDEXNumber for beachgoers
UVINDEXIt drops to 0 after sundown
UVINDEXScale with the highest reading at midday, usually
UVINDEXNumber affected by cloud cover