| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 41°F | 59°F | 50°F | 2.8" |
| February | 45°F | 62°F | 53°F | 3.1" |
| March | 47°F | 65°F | 55°F | 2.9" |
| April | 49°F | 67°F | 57°F | 1.8" |
| May | 52°F | 69°F | 59°F | 0.4" |
| June | 54°F | 72°F | 62°F | 0.3" |
| July | 56°F | 73°F | 63°F | 0.0" |
| August | 57°F | 73°F | 63°F | 0.0" |
| September | 55°F | 76°F | 64°F | 0.1" |
| October | 52°F | 73°F | 61°F | 1.0" |
| November | 47°F | 65°F | 56°F | 1.9" |
| December | 42°F | 59°F | 50°F | 4.1" |
| Index | San Leandro | California | National |
| Air quality index | 40 | 55 | 42 |
| Pollution index | 6,427,290 | 10,473,190 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 290 |
| Days with moderate air quality | 74 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.110% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.010% |
| Mercury | 0.003% |
| City | Population | Air Quality Index | National Avg. |
| South San Francisco, CA | 66,878 | 40 | 20.0% |
| El Cerrito CDP, CA | 5,699 | 40 | 20.0% |
| Castle Hill, CA | 1,164 | 40 | 20.0% |
| San Miguel, CA | 3,253 | 40 | 20.0% |
| Ashland, CA | 23,566 | 40 | 20.0% |
| San Leandro, CA | 90,489 | 40 | 20.0% |
| City | Population | Air Quality Index | National Avg. |
| Bellingham, WA | 90,821 | 34 | 32.0% |
| Westminster, CA | 90,857 | 72 | 44.0% |
| Toms River, NJ | 90,081 | 41 | 18.0% |
| Santa Barbara, CA | 90,911 | 44 | 12.0% |
| Indio, CA | 89,996 | 89 | 78.0% |
| San Leandro, CA | 90,489 | 40 | 20.0% |
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