| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 48°F | 70°F | 58°F | 3.5" |
| February | 50°F | 70°F | 59°F | 2.9" |
| March | 52°F | 72°F | 61°F | 1.5" |
| April | 55°F | 74°F | 63°F | 0.7" |
| May | 58°F | 75°F | 65°F | 0.5" |
| June | 61°F | 78°F | 68°F | 0.0" |
| July | 65°F | 83°F | 72°F | 0.0" |
| August | 65°F | 84°F | 73°F | 0.0" |
| September | 64°F | 85°F | 72°F | 0.3" |
| October | 60°F | 81°F | 69°F | 0.7" |
| November | 54°F | 75°F | 63°F | 0.8" |
| December | 48°F | 69°F | 57°F | 2.8" |
| Index | San Marino | California | National |
| Air quality index | 72 | 55 | 42 |
| Pollution index | 139,490,000 | 10,473,190 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 66 |
| Days with moderate air quality | 208 |
| Days w/ poor A.Q. for sensitive groups | 62 |
| Days with unhealthy air quality | 28 |
| Pollutant | Total |
| Arsenic | 0.200% |
| Benzene | 0.950% |
| Carbon Tetrachloride | 0.080% |
| Lead | 1.320% |
| Mercury | 0.440% |
| City | Population | Air Quality Index | National Avg. |
| Azusa, CA | 49,584 | 72 | 44.0% |
| Citrus, CA | 10,105 | 72 | 44.0% |
| Irwindale, CA | 1,365 | 72 | 44.0% |
| Valinda, CA | 22,665 | 72 | 44.0% |
| West Puente Valley, CA | 23,555 | 72 | 44.0% |
| San Marino, CA | 13,020 | 72 | 44.0% |
| City | Population | Air Quality Index | National Avg. |
| Lloydminster (Part), SK | 13,022 | n/a | |
| Coolidge, AZ | 13,016 | 74 | 48.0% |
| Red Oak, TX | 13,010 | 51 | 2.0% |
| Butler, PA | 13,008 | 31 | 38.0% |
| Dunmore, PA | 13,008 | 38 | 24.0% |
| San Marino, CA | 13,020 | 72 | 44.0% |
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