| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 9°F | 26°F | 17°F | 1.0" |
| February | 13°F | 30°F | 21°F | 1.0" |
| March | 27°F | 48°F | 36°F | 6.5" |
| April | 37°F | 62°F | 49°F | 6.0" |
| May | 51°F | 73°F | 61°F | 5.9" |
| June | 61°F | 84°F | 72°F | 4.4" |
| July | 63°F | 87°F | 75°F | 7.6" |
| August | 61°F | 83°F | 71°F | 7.9" |
| September | 54°F | 79°F | 65°F | 6.8" |
| October | 41°F | 65°F | 52°F | 3.1" |
| November | 25°F | 47°F | 35°F | 3.7" |
| December | 9°F | 25°F | 17°F | 1.0" |
| Index | Greenville | Iowa | National |
| Air quality index | 35 | 39 | 42 |
| Pollution index | 769,697 | 1,154,535 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 322 |
| Days with moderate air quality | 42 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.002% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Ruthven, IA | 771 | 15 | 70.0% |
| Royal, IA | 505 | 35 | 30.0% |
| Peterson, IA | 483 | 35 | 30.0% |
| Dickens, IA | 206 | 35 | 30.0% |
| Spencer, IA | 11,038 | 35 | 30.0% |
| Greenville, IA | 62 | 35 | 30.0% |
| City | Population | Air Quality Index | National Avg. |
| Port Heiden, AK | 62 | 31 | 38.0% |
| Goldfield, CO | 62 | 16 | 68.0% |
| Istachatta, FL | 62 | 30 | 40.0% |
| Homestead, IA | 62 | 39 | 22.0% |
| Northboro, IA | 62 | 40 | 20.0% |
| Greenville, IA | 62 | 35 | 30.0% |
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