https://www.willyweather.com/ca/riverside-county/perris.html

Weather

In general, Perris has a sunny, mild Mediterranean climate.

On average, Perris gets only 10 inches of rain per year. The humidy is quite low all year. The July high temperatures average 97 degrees, while January low temperatures average 35 degrees. There are 275 sunny days per year.

Air and Water Quality

• Air quality in Perris, CA is 13 on a scale to 100 (higher is better). This is based on ozone alert days and number of pollutants in the air, as reported by the EPA.

• Water quality in Perris, CA is 50 on a scale to 100 (higher is better). The EPA has a complex method of measuring watershed quality using 15 indicators.