| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 2°F | 19°F | 10°F | 2.0" |
| February | 8°F | 25°F | 15°F | 0.7" |
| March | 22°F | 39°F | 29°F | 3.3" |
| April | 36°F | 54°F | 44°F | 3.8" |
| May | 48°F | 69°F | 57°F | 3.9" |
| June | 57°F | 76°F | 65°F | 4.2" |
| July | 62°F | 81°F | 71°F | 3.9" |
| August | 59°F | 80°F | 69°F | 4.7" |
| September | 51°F | 72°F | 60°F | 5.5" |
| October | 38°F | 56°F | 46°F | 4.9" |
| November | 27°F | 42°F | 34°F | 3.7" |
| December | 6°F | 22°F | 14°F | 1.0" |
| Index | Donnelly | Minnesota | National |
| Air quality index | 25 | 35 | 42 |
| Pollution index | 454,047 | 1,854,519 | 2,726,193 |
| Measurement | Total |
| Days measured | 361 |
| Days with good air quality | 325 |
| Days with moderate air quality | 36 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| 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. |
| Alberta, MN | 154 | 25 | 50.0% |
| Chokio, MN | 424 | 25 | 50.0% |
| Johnson, MN | 14 | 25 | 50.0% |
| Morris, MN | 5,519 | 25 | 50.0% |
| Herman, MN | 534 | 25 | 50.0% |
| Donnelly, MN | 259 | 25 | 50.0% |
| City | Population | Air Quality Index | National Avg. |
| Oxbow Estates, AZ | 259 | 60 | 20.0% |
| Groveland, CA | 259 | 39 | 22.0% |
| Jamaica, IA | 259 | 37 | 26.0% |
| Saratoga, IN | 259 | 35 | 30.0% |
| Spring Lake, IN | 259 | 54 | 8.0% |
| Donnelly, MN | 259 | 25 | 50.0% |