| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 44°F | 69°F | 56°F | 2.3" |
| February | 45°F | 70°F | 57°F | 2.0" |
| March | 48°F | 74°F | 60°F | 1.2" |
| April | 51°F | 77°F | 62°F | 0.7" |
| May | 55°F | 81°F | 66°F | 0.4" |
| June | 60°F | 88°F | 72°F | 0.0" |
| July | 65°F | 94°F | 77°F | 0.1" |
| August | 65°F | 95°F | 78°F | 0.0" |
| September | 64°F | 93°F | 76°F | 0.2" |
| October | 57°F | 84°F | 69°F | 0.4" |
| November | 49°F | 77°F | 62°F | 0.6" |
| December | 43°F | 68°F | 55°F | 2.6" |
| Index | San Dimas | California | National |
| Air quality index | 89 | 55 | 50 |
| Pollution index | 139,490,000 | 18,106,726 | 5,066,862 |
| 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 | 0.200% |
| Benzene | 0.950% |
| Carbon Tetrachloride | 0.080% |
| Lead | 1.320% |
| Mercury | 0.440% |
| City, State | Population | Air Quality Index | National Avg. |
| La Mirada, CA | 49,130 | 72 | 44% |
| Whittier, CA | 86,630 | 72 | 44% |
| Monrovia, CA | 37,090 | 72 | 44% |
| El Monte, CA | 115,665 | 72 | 44% |
| Sierra Madre, CA | 11,067 | 72 | 44% |
| San Dimas, CA | 34,109 | 89 | 78% |
| City, State | Population | Air Quality Index | National Avg. |
| Bay City, MI | 34,110 | 26 | 48% |
| Redan, GA | 34,100 | 52 | 4% |
| Seaside, CA | 34,120 | 37 | 26% |
| Hinesville, GA | 34,127 | 39 | 22% |
| Dakota Ridge, CO | 34,133 | 47 | 6% |
| San Dimas, CA | 34,109 | 89 | 78% |
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