| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 29°F | 43°F | 35°F | 1.8" |
| February | 33°F | 49°F | 39°F | 1.4" |
| March | 38°F | 58°F | 47°F | 2.6" |
| April | 42°F | 64°F | 52°F | 2.0" |
| May | 49°F | 74°F | 60°F | 1.8" |
| June | 55°F | 82°F | 67°F | 1.5" |
| July | 63°F | 93°F | 77°F | 0.3" |
| August | 62°F | 91°F | 76°F | 0.2" |
| September | 54°F | 81°F | 66°F | 0.6" |
| October | 44°F | 66°F | 54°F | 1.7" |
| November | 36°F | 51°F | 43°F | 2.3" |
| December | 28°F | 41°F | 34°F | 2.5" |
| Index | Dayton | Washington | National |
| Air quality index | 23 | 36 | 42 |
| Pollution index | 1,232,200 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 318 |
| Days with moderate air quality | 47 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.020% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Waitsburg, WA | 1,177 | 23 | 54.0% |
| Dixie, WA | 170 | 23 | 54.0% |
| Starbuck, WA | 161 | 23 | 54.0% |
| Dayton, WA | 2,620 | 23 | 54.0% |
| City | Population | Air Quality Index | National Avg. |
| Eldora, IA | 2,620 | 37 | 26.0% |
| Homestead Valley, CA | 2,619 | 89 | 78.0% |
| Rose Hills, CA | 2,619 | 72 | 44.0% |
| Clarkson Valley, MO | 2,619 | 54 | 8.0% |
| Indian Springs Village, AL | 2,618 | 53 | 6.0% |
| Dayton, WA | 2,620 | 23 | 54.0% |
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