| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 3°F | 20°F | 11°F | 5.3" |
| February | 4°F | 22°F | 12°F | 1.7" |
| March | 21°F | 38°F | 28°F | 2.5" |
| April | 34°F | 54°F | 43°F | 3.2" |
| May | 46°F | 69°F | 56°F | 4.5" |
| June | 56°F | 77°F | 66°F | 7.4" |
| July | 60°F | 83°F | 71°F | 6.3" |
| August | 57°F | 79°F | 67°F | 2.9" |
| September | 49°F | 72°F | 60°F | 3.7" |
| October | 38°F | 57°F | 46°F | 7.1" |
| November | 24°F | 41°F | 32°F | 0.9" |
| December | 7°F | 23°F | 15°F | 0.7" |
| Index | Milnor | North Dakota | National |
| Air quality index | 33 | 35 | 42 |
| Pollution index | 445,308 | 1,038,665 | 2,726,193 |
| Measurement | Total |
| Days measured | 363 |
| Days with good air quality | 327 |
| Days with moderate air quality | 34 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 1 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.003% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Forman, ND | 490 | 20 | 60.0% |
| Rutland, ND | 137 | 20 | 60.0% |
| De Lamere, ND | 11 | 33 | 34.0% |
| Lisbon, ND | 1,829 | 33 | 34.0% |
| McLeod, ND | 10 | 33 | 34.0% |
| Milnor, ND | 707 | 33 | 34.0% |
| City | Population | Air Quality Index | National Avg. |
| Vicksburg, AZ | 707 | 13 | 74.0% |
| Westley, CA | 707 | 49 | 2.0% |
| Brighton, IA | 707 | 35 | 30.0% |
| Spencer, OH | 707 | 43 | 14.0% |
| Colman, SD | 707 | 42 | 16.0% |
| Milnor, ND | 707 | 33 | 34.0% |