| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 9°F | 24°F | 16°F | 0.8" |
| February | 11°F | 28°F | 18°F | 1.4" |
| March | 26°F | 44°F | 33°F | 2.1" |
| April | 37°F | 58°F | 46°F | 3.5" |
| May | 48°F | 70°F | 58°F | 5.7" |
| June | 58°F | 79°F | 68°F | 5.6" |
| July | 62°F | 83°F | 72°F | 5.9" |
| August | 59°F | 79°F | 69°F | 6.5" |
| September | 52°F | 74°F | 61°F | 4.8" |
| October | 39°F | 60°F | 48°F | 7.9" |
| November | 26°F | 45°F | 34°F | 2.6" |
| December | 12°F | 27°F | 19°F | 0.7" |
| Index | Ashton | Iowa | National |
| Air quality index | 36 | 39 | 42 |
| Pollution index | 627,200 | 1,154,535 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 321 |
| Days with moderate air quality | 43 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Archer, IA | 116 | 35 | 30.0% |
| Sibley, IA | 2,599 | 36 | 28.0% |
| Melvin, IA | 237 | 36 | 28.0% |
| Ellsworth, MN | 522 | 36 | 28.0% |
| George, IA | 1,011 | 36 | 28.0% |
| Ashton, IA | 535 | 36 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Nuiqsut, AK | 535 | 38 | 24.0% |
| Arden, DE | 535 | 51 | 2.0% |
| Crawfordville, GA | 535 | 44 | 12.0% |
| Creston, IL | 535 | 42 | 16.0% |
| Riverwood, KY | 535 | 49 | 2.0% |
| Ashton, IA | 535 | 36 | 28.0% |
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