| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 36°F | 48°F | 41°F | 7.8" |
| February | 37°F | 53°F | 44°F | 4.4" |
| March | 40°F | 58°F | 47°F | 5.7" |
| April | 41°F | 64°F | 51°F | 3.3" |
| May | 46°F | 73°F | 57°F | 3.5" |
| June | 51°F | 78°F | 62°F | 1.9" |
| July | 54°F | 86°F | 68°F | 3.3" |
| August | 54°F | 86°F | 68°F | 2.1" |
| September | 49°F | 80°F | 63°F | 3.4" |
| October | 44°F | 67°F | 54°F | 5.6" |
| November | 40°F | 55°F | 46°F | 5.4" |
| December | 35°F | 47°F | 40°F | 7.2" |
| Index | Halsey | Oregon | National |
| Air quality index | 17 | 32 | 42 |
| Pollution index | 3,182,180 | 7,156,356 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 332 |
| Days with moderate air quality | 33 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| 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. |
| Monroe, OR | 643 | 17 | 66.0% |
| Corvallis, OR | 58,612 | 17 | 66.0% |
| Peoria, OR | 216 | 17 | 66.0% |
| Philomath, OR | 5,143 | 17 | 66.0% |
| Alpine, OR | 215 | 17 | 66.0% |
| Halsey, OR | 1,139 | 17 | 66.0% |
| City | Population | Air Quality Index | National Avg. |
| Rison, AR | 1,139 | 32 | 36.0% |
| Lake Riverside, CA | 1,139 | 89 | 78.0% |
| Fowler, CO | 1,139 | 20 | 60.0% |
| Converse, IN | 1,139 | 37 | 26.0% |
| Morristown, IN | 1,139 | 28 | 44.0% |
| Halsey, OR | 1,139 | 17 | 66.0% |
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