| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 38°F | 58°F | 47°F | 3.3" |
| February | 41°F | 63°F | 51°F | 3.1" |
| March | 44°F | 68°F | 55°F | 2.9" |
| April | 47°F | 74°F | 59°F | 1.8" |
| May | 52°F | 82°F | 65°F | 0.5" |
| June | 57°F | 90°F | 71°F | 0.3" |
| July | 59°F | 95°F | 74°F | 0.0" |
| August | 58°F | 93°F | 73°F | 0.0" |
| September | 56°F | 90°F | 70°F | 0.1" |
| October | 50°F | 79°F | 63°F | 1.2" |
| November | 43°F | 66°F | 53°F | 1.6" |
| December | 38°F | 57°F | 47°F | 3.8" |
| Index | Clay | California | National |
| Air quality index | 55 | 55 | 50 |
| Pollution index | 15,476,500 | 18,106,726 | 5,066,862 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 155 |
| Days with moderate air quality | 175 |
| Days w/ poor A.Q. for sensitive groups | 31 |
| Days with unhealthy air quality | 4 |
| Pollutant | Total |
| Arsenic | 0.090% |
| Benzene | 0.130% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.130% |
| Mercury | 0.070% |
| City, State | Population | Air Quality Index | National Avg. |
| Elk Grove, CA | 163,634 | 55 | 10% |
| Ione, CA | 7,056 | 55 | 10% |
| Wilton, CA | 4,995 | 55 | 10% |
| Florin, CA | 49,486 | 55 | 10% |
| Vineyard, CA | 26,650 | 55 | 10% |
| Clay, CA | 1,209 | 55 | 10% |
| City, State | Population | Air Quality Index | National Avg. |
| Celoron, NY | 1,209 | 33 | 34% |
| Markle, IN | 1,209 | 33 | 34% |
| Cottage City, MD | 1,209 | 49 | 2% |
| Branchville, SC | 1,209 | 34 | 32% |
| Lenape Heights, PA | 1,209 | 36 | 28% |
| Clay, CA | 1,209 | 55 | 10% |