| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 19°F | 47°F | 31°F | n/a |
| February | 25°F | 51°F | 37°F | n/a |
| March | 30°F | 58°F | 43°F | n/a |
| April | 31°F | 63°F | 47°F | n/a |
| May | 40°F | 70°F | 55°F | n/a |
| June | 48°F | 80°F | 65°F | n/a |
| July | 56°F | 90°F | 74°F | n/a |
| August | 51°F | 86°F | 70°F | n/a |
| September | 47°F | 79°F | 63°F | n/a |
| October | 34°F | 68°F | 50°F | n/a |
| November | 28°F | 55°F | 40°F | n/a |
| December | 19°F | 44°F | 30°F | n/a |
| Index | Johnstonville | California | National |
| Air quality index | 46 | 55 | 42 |
| Pollution index | 1,799,830 | 10,473,190 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 244 |
| Days with moderate air quality | 121 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.010% |
| Mercury | 0.004% |
| City | Population | Air Quality Index | National Avg. |
| Janesville, CA | 2,803 | 46 | 8.0% |
| Litchfield, CA | 183 | 46 | 8.0% |
| Susanville, CA | 14,922 | 46 | 8.0% |
| Johnstonville, CA | 1,151 | 46 | 8.0% |
| City | Population | Air Quality Index | National Avg. |
| Clarence, IA | 1,151 | 35 | 30.0% |
| Chevy Chase View, MD | 1,151 | 47 | 6.0% |
| Crenshaw, MS | 1,151 | 45 | 10.0% |
| Botkins, OH | 1,151 | 39 | 22.0% |
| Marshallton, PA | 1,151 | 42 | 16.0% |
| Johnstonville, CA | 1,151 | 46 | 8.0% |
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