| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 17°F | 34°F | 25°F | 0.7" |
| February | 18°F | 36°F | 26°F | 2.1" |
| March | 33°F | 53°F | 41°F | 4.1" |
| April | 43°F | 66°F | 53°F | 4.8" |
| May | 53°F | 75°F | 63°F | 6.2" |
| June | 63°F | 84°F | 73°F | 5.9" |
| July | 65°F | 86°F | 75°F | 5.6" |
| August | 63°F | 84°F | 73°F | 2.0" |
| September | 55°F | 79°F | 65°F | 4.1" |
| October | 44°F | 66°F | 54°F | 6.1" |
| November | 33°F | 51°F | 41°F | 3.3" |
| December | 22°F | 38°F | 30°F | 3.1" |
| Index | Mount Union | Iowa | National |
| Air quality index | 32 | 39 | 42 |
| Pollution index | 871,264 | 1,154,535 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 300 |
| Days with moderate air quality | 65 |
| 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 | 0.001% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Beaverdale, IA | 918 | 29 | 42.0% |
| Mount Pleasant, IA | 8,795 | 29 | 42.0% |
| Danville, IA | 963 | 29 | 42.0% |
| New London, IA | 2,520 | 29 | 42.0% |
| Salem, IA | 507 | 29 | 42.0% |
| Mount Union, IA | 140 | 32 | 36.0% |
| City | Population | Air Quality Index | National Avg. |
| Atqasuk, AK | 140 | 38 | 24.0% |
| Minto, AK | 140 | 38 | 24.0% |
| Springtown, AR | 140 | 44 | 12.0% |
| San Acacio, CO | 140 | 15 | 70.0% |
| Bridgewater, IA | 140 | 39 | 22.0% |
| Mount Union, IA | 140 | 32 | 36.0% |