| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 34°F | 49°F | 41°F | 5.6" |
| February | 35°F | 53°F | 43°F | 4.1" |
| March | 37°F | 58°F | 47°F | 5.4" |
| April | 39°F | 63°F | 50°F | 2.9" |
| May | 45°F | 71°F | 57°F | 2.3" |
| June | 50°F | 76°F | 62°F | 1.3" |
| July | 54°F | 86°F | 69°F | 0.3" |
| August | 54°F | 86°F | 69°F | 0.4" |
| September | 50°F | 80°F | 63°F | 1.8" |
| October | 43°F | 66°F | 54°F | 4.1" |
| November | 38°F | 55°F | 46°F | 6.7" |
| December | 33°F | 48°F | 40°F | 7.4" |
| Index | Jefferson | Oregon | National |
| Air quality index | 28 | 32 | 42 |
| Pollution index | 3,182,180 | 7,156,356 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 280 |
| Days with moderate air quality | 83 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.040% |
| Carbon Tetrachloride | 0.030% |
| Lead | 0.190% |
| Mercury | 0.110% |
| City | Population | Air Quality Index | National Avg. |
| Corvallis, OR | 58,612 | 17 | 66.0% |
| Lacomb, OR | 581 | 28 | 44.0% |
| South Lebanon, OR | 903 | 28 | 44.0% |
| Tangent, OR | 1,394 | 28 | 44.0% |
| Lebanon, OR | 17,144 | 28 | 44.0% |
| Jefferson, OR | 3,348 | 28 | 44.0% |
| City | Population | Air Quality Index | National Avg. |
| Hoopa, CA | 3,348 | 27 | 46.0% |
| Flagler Estates, FL | 3,348 | 17 | 66.0% |
| Grande-Rivière, QC | 3,348 | n/a | |
| Perry, NY | 3,347 | 37 | 26.0% |
| Sharpsburg, PA | 3,347 | 56 | 12.0% |
| Jefferson, OR | 3,348 | 28 | 44.0% |
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