| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 41°F | 61°F | 50°F | 2.5" |
| February | 44°F | 64°F | 53°F | 2.5" |
| March | 46°F | 68°F | 56°F | 2.1" |
| April | 48°F | 71°F | 58°F | 1.3" |
| May | 52°F | 75°F | 62°F | 0.3" |
| June | 56°F | 80°F | 66°F | 0.2" |
| July | 58°F | 82°F | 68°F | 0.0" |
| August | 58°F | 82°F | 68°F | 0.0" |
| September | 57°F | 82°F | 67°F | 0.1" |
| October | 53°F | 77°F | 63°F | 0.6" |
| November | 46°F | 68°F | 56°F | 1.3" |
| December | 41°F | 61°F | 50°F | 2.4" |
| Index | Monte Sereno | California | National |
| Air quality index | 43 | 55 | 42 |
| Pollution index | 11,477,200 | 10,473,190 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 263 |
| Days with moderate air quality | 98 |
| Days w/ poor A.Q. for sensitive groups | 4 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.070% |
| Benzene | 0.110% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.160% |
| Mercury | 0.090% |
| City | Population | Air Quality Index | National Avg. |
| Brookdale, CA | 1,345 | 35 | 30.0% |
| Felton, CA | 3,290 | 35 | 30.0% |
| Zayante, CA | 789 | 35 | 30.0% |
| Mount Hermon, CA | 1,427 | 35 | 30.0% |
| Lexington Hills, CA | 2,745 | 35 | 30.0% |
| Monte Sereno, CA | 3,621 | 43 | 14.0% |
| City | Population | Air Quality Index | National Avg. |
| Yuma, CO | 3,621 | 45 | 10.0% |
| Oxford, MI | 3,621 | 38 | 24.0% |
| Lyons, KS | 3,619 | 40 | 20.0% |
| St. Johns, AZ | 3,623 | 44 | 12.0% |
| Park City, TN | 3,623 | 44 | 12.0% |
| Monte Sereno, CA | 3,621 | 43 | 14.0% |