| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 36°F | 51°F | 42°F | 4.6" |
| February | 38°F | 56°F | 45°F | 3.7" |
| March | 40°F | 60°F | 48°F | 4.4" |
| April | 42°F | 65°F | 52°F | 2.5" |
| May | 48°F | 74°F | 59°F | 2.0" |
| June | 53°F | 79°F | 64°F | 1.0" |
| July | 57°F | 88°F | 71°F | 0.3" |
| August | 57°F | 89°F | 71°F | 0.2" |
| September | 52°F | 83°F | 65°F | 0.9" |
| October | 46°F | 69°F | 55°F | 2.8" |
| November | 41°F | 56°F | 47°F | 5.0" |
| December | 36°F | 49°F | 41°F | 6.3" |
| Index | Tri-City | Oregon | National |
| Air quality index | 24 | 32 | 42 |
| Pollution index | 13,842,600 | 7,156,356 | 2,726,193 |
| Measurement | Total |
| Days measured | 347 |
| Days with good air quality | 288 |
| Days with moderate air quality | 59 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.020% |
| Benzene | 0.210% |
| Carbon Tetrachloride | 0.030% |
| Lead | 0.030% |
| Mercury | 0.020% |
| City | Population | Air Quality Index | National Avg. |
| Dillard, OR | 525 | 24 | 52.0% |
| Winston, OR | 5,444 | 24 | 52.0% |
| Green, OR | 8,149 | 24 | 52.0% |
| Canyonville, OR | 1,812 | 24 | 52.0% |
| Lookingglass, OR | 862 | 24 | 52.0% |
| Tri-City, OR | 4,449 | 24 | 52.0% |
| City | Population | Air Quality Index | National Avg. |
| Millsboro, DE | 4,448 | 36 | 28.0% |
| Saukville, WI | 4,448 | 44 | 12.0% |
| Sullivan, IL | 4,450 | 44 | 12.0% |
| Florence, MS | 4,446 | 44 | 12.0% |
| Montoursville, PA | 4,452 | 35 | 30.0% |
| Tri-City, OR | 4,449 | 24 | 52.0% |
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