| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 3°F | 22°F | 12°F | 0.9" |
| February | 4°F | 25°F | 15°F | 1.0" |
| March | 17°F | 38°F | 28°F | 1.5" |
| April | 30°F | 52°F | 40°F | 2.5" |
| May | 40°F | 64°F | 51°F | 4.0" |
| June | 49°F | 74°F | 61°F | 4.7" |
| July | 56°F | 80°F | 68°F | 3.4" |
| August | 54°F | 77°F | 65°F | 4.5" |
| September | 47°F | 70°F | 58°F | 3.2" |
| October | 36°F | 55°F | 45°F | 3.2" |
| November | 23°F | 40°F | 31°F | 1.7" |
| December | 9°F | 25°F | 16°F | 1.7" |
| Index | Cromwell | Minnesota | National |
| Air quality index | 35 | 35 | 42 |
| Pollution index | 521,015 | 1,854,519 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 326 |
| Days with moderate air quality | 38 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.003% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Barnum, MN | 630 | 35 | 30.0% |
| Wright, MN | 140 | 35 | 30.0% |
| Brookston, MN | 119 | 35 | 30.0% |
| Kettle River, MN | 164 | 35 | 30.0% |
| Tamarack, MN | 105 | 35 | 30.0% |
| Cromwell, MN | 370 | 35 | 30.0% |
| City | Population | Air Quality Index | National Avg. |
| East Point, AL | 370 | 41 | 18.0% |
| Shonto, AZ | 370 | 45 | 10.0% |
| Higgston, GA | 370 | 26 | 48.0% |
| Protection, KS | 370 | 15 | 70.0% |
| Willisburg, KY | 370 | 49 | 2.0% |
| Cromwell, MN | 370 | 35 | 30.0% |