| 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 | Winfield | 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. |
| Rome, IA | 70 | 29 | 42.0% |
| Mediapolis, IA | 2,118 | 29 | 42.0% |
| Westwood, IA | 71 | 29 | 42.0% |
| Mount Pleasant, IA | 8,574 | 29 | 42.0% |
| New London, IA | 2,433 | 29 | 42.0% |
| Winfield, IA | 1,035 | 32 | 36.0% |
| City | Population | Air Quality Index | National Avg. |
| Sloan, IA | 1,035 | 35 | 30.0% |
| Theresa, NY | 1,035 | 35 | 30.0% |
| Ivyland, PA | 1,035 | 51 | 2.0% |
| Rio Vista, TX | 1,035 | 33 | 34.0% |
| Low, QC | 1,035 | n/a | |
| Winfield, IA | 1,035 | 32 | 36.0% |
Here are the best places to live in Iowa
These are the largest cities in Iowa
See the best places to live in Winfield
Check out the 10 most dangerous cities in Iowa