| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 41°F | 69°F | 54°F | 11.3" |
| February | 41°F | 71°F | 55°F | 4.5" |
| March | 41°F | 76°F | 58°F | 2.0" |
| April | 44°F | 78°F | 61°F | 1.7" |
| May | 48°F | 79°F | 64°F | 0.8" |
| June | 54°F | 86°F | 69°F | 0.0" |
| July | 59°F | 90°F | 74°F | 0.1" |
| August | 58°F | 92°F | 74°F | 0.1" |
| September | 53°F | 90°F | 71°F | 2.2" |
| October | 49°F | 83°F | 65°F | 2.4" |
| November | 42°F | 78°F | 59°F | 3.4" |
| December | 39°F | 68°F | 52°F | 11.0" |
| Index | Norco | California | National |
| Air quality index | 89 | 55 | 42 |
| Pollution index | 22,790,900 | 10,473,190 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 42 |
| Days with moderate air quality | 178 |
| Days w/ poor A.Q. for sensitive groups | 79 |
| Days with unhealthy air quality | 58 |
| Pollutant | Total |
| Arsenic | 0.060% |
| Benzene | 0.190% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.220% |
| Mercury | 0.230% |
| City | Population | Air Quality Index | National Avg. |
| Bloomington, CA | 21,907 | 89 | 78.0% |
| Jurupa Valley, CA | 106,646 | 89 | 78.0% |
| Claremont, CA | 35,610 | 89 | 78.0% |
| La Verne, CA | 32,346 | 89 | 78.0% |
| Rancho Cucamonga, CA | 178,060 | 89 | 78.0% |
| Norco, CA | 27,021 | 89 | 78.0% |
| City | Population | Air Quality Index | National Avg. |
| Magna, UT | 27,029 | 51 | 2.0% |
| Mount Pleasant, WI | 27,008 | 39 | 22.0% |
| New London, CT | 27,001 | 37 | 26.0% |
| Wakefield, MA | 27,041 | 43 | 14.0% |
| West Chicago, IL | 26,998 | 55 | 10.0% |
| Norco, CA | 27,021 | 89 | 78.0% |
Here are the best places to live in California
Most Dangerous Cities In The US
Safest States In The US
Check out the 10 safest cities in California