| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 38°F | 59°F | 47°F | 2.6" |
| February | 41°F | 63°F | 51°F | 2.6" |
| March | 43°F | 67°F | 54°F | 2.1" |
| April | 45°F | 72°F | 57°F | 1.4" |
| May | 50°F | 78°F | 62°F | 0.3" |
| June | 54°F | 85°F | 67°F | 0.2" |
| July | 58°F | 90°F | 71°F | 0.0" |
| August | 57°F | 89°F | 70°F | 0.0" |
| September | 56°F | 88°F | 69°F | 0.1" |
| October | 50°F | 79°F | 63°F | 0.9" |
| November | 43°F | 67°F | 54°F | 1.5" |
| December | 38°F | 60°F | 48°F | 2.8" |
| Index | Blackhawk | California | National |
| Air quality index | 40 | 55 | 42 |
| Pollution index | 13,698,500 | 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 | 0.040% |
| Benzene | 0.110% |
| Carbon Tetrachloride | 0.330% |
| Lead | 0.070% |
| Mercury | 0.120% |
| City | Population | Air Quality Index | National Avg. |
| Acalanes Ridge, CA | 875 | 40 | 20.0% |
| Concord, CA | 129,227 | 40 | 20.0% |
| North Gate, CA | 740 | 40 | 20.0% |
| Reliez Valley, CA | 3,321 | 40 | 20.0% |
| Shell Ridge, CA | 1,081 | 40 | 20.0% |
| Blackhawk, CA | 10,590 | 40 | 20.0% |
| City | Population | Air Quality Index | National Avg. |
| Morro Bay, CA | 10,592 | 46 | 8.0% |
| North Branch, MN | 10,585 | 46 | 8.0% |
| Martin, TN | 10,585 | 26 | 48.0% |
| Jackson, WY | 10,585 | 43 | 14.0% |
| Greentree, NJ | 10,597 | 51 | 2.0% |
| Blackhawk, CA | 10,590 | 40 | 20.0% |
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