| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 35°F | 48°F | 40°F | 4.8" |
| February | 36°F | 53°F | 43°F | 4.0" |
| March | 39°F | 57°F | 47°F | 5.0" |
| April | 40°F | 62°F | 50°F | 2.8" |
| May | 45°F | 70°F | 56°F | 1.8" |
| June | 49°F | 76°F | 61°F | 1.2" |
| July | 53°F | 85°F | 68°F | 0.2" |
| August | 52°F | 86°F | 68°F | 0.3" |
| September | 49°F | 80°F | 63°F | 1.2" |
| October | 43°F | 66°F | 54°F | 3.9" |
| November | 39°F | 54°F | 46°F | 6.3" |
| December | 34°F | 47°F | 40°F | 6.2" |
| Index | Dayton | Oregon | National |
| Air quality index | 32 | 32 | 42 |
| Pollution index | 3,182,180 | 7,156,356 | 2,726,193 |
| Measurement | Total |
| Days measured | 356 |
| Days with good air quality | 302 |
| Days with moderate air quality | 54 |
| 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. |
| McMinnville, OR | 34,466 | 32 | 36.0% |
| Amity, OR | 1,557 | 32 | 36.0% |
| Keizer, OR | 39,408 | 32 | 36.0% |
| St. Paul, OR | 396 | 32 | 36.0% |
| Woodburn, OR | 26,008 | 32 | 36.0% |
| Dayton, OR | 2,726 | 32 | 36.0% |
| City | Population | Air Quality Index | National Avg. |
| Clarion, IA | 2,726 | 15 | 70.0% |
| Cokato, MN | 2,726 | 32 | 36.0% |
| Gervais, OR | 2,726 | 32 | 36.0% |
| Beach City, TX | 2,726 | 52 | 4.0% |
| Parksdale, CA | 2,725 | 50 | = 100 |
| Dayton, OR | 2,726 | 32 | 36.0% |
Here are the best places to live in Oregon
10 best cities to buy a new house in Oregon
Top 10 best public schools in Dayton
These are the 10 most affordable cities in Oregon