| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 36°F | 60°F | 46°F | 6.0" |
| February | 39°F | 64°F | 50°F | 5.7" |
| March | 41°F | 67°F | 52°F | 4.6" |
| April | 43°F | 71°F | 55°F | 2.4" |
| May | 46°F | 77°F | 60°F | 1.1" |
| June | 50°F | 83°F | 64°F | 0.4" |
| July | 52°F | 85°F | 65°F | 0.0" |
| August | 52°F | 84°F | 64°F | 0.0" |
| September | 49°F | 85°F | 64°F | 0.2" |
| October | 46°F | 78°F | 59°F | 2.0" |
| November | 41°F | 67°F | 52°F | 3.2" |
| December | 36°F | 59°F | 46°F | 6.9" |
| Index | Sebastopol | California | National |
| Air quality index | 34 | 55 | 42 |
| Pollution index | 7,898,290 | 10,473,190 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 346 |
| Days with moderate air quality | 18 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 1 |
| Pollutant | Total |
| Arsenic | 0.260% |
| Benzene | 0.080% |
| Carbon Tetrachloride | 0.005% |
| Lead | 0.240% |
| Mercury | 0.270% |
| City | Population | Air Quality Index | National Avg. |
| Calistoga, CA | 5,346 | 34 | 32.0% |
| Penngrove, CA | 2,368 | 34 | 32.0% |
| Santa Rosa, CA | 178,391 | 34 | 32.0% |
| Carmet, CA | 0 | 34 | 32.0% |
| Guerneville, CA | 4,747 | 34 | 32.0% |
| Sebastopol, CA | 7,664 | 34 | 32.0% |
| City | Population | Air Quality Index | National Avg. |
| Monahans, TX | 7,667 | 28 | 44.0% |
| Perry, IA | 7,660 | 37 | 26.0% |
| Caribou, ME | 7,659 | 31 | 38.0% |
| Butler, NJ | 7,669 | 51 | 2.0% |
| Waller, WA | 7,672 | 30 | 40.0% |
| Sebastopol, CA | 7,664 | 34 | 32.0% |
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