| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 2°F | 21°F | 11°F | 0.8" |
| February | 3°F | 24°F | 13°F | 2.5" |
| March | 18°F | 39°F | 28°F | 3.2" |
| April | 30°F | 52°F | 40°F | 4.2" |
| May | 40°F | 65°F | 52°F | 3.0" |
| June | 50°F | 73°F | 61°F | 6.3" |
| July | 55°F | 79°F | 67°F | 6.2" |
| August | 53°F | 77°F | 64°F | 9.2" |
| September | 45°F | 68°F | 56°F | 9.7" |
| October | 35°F | 53°F | 44°F | 5.1" |
| November | 23°F | 38°F | 30°F | 2.8" |
| December | 8°F | 23°F | 15°F | 1.6" |
| Index | Mountain Iron | Minnesota | National |
| Air quality index | 35 | 35 | 42 |
| Pollution index | 9,390,680 | 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 | 1.380% |
| Benzene | 0.110% |
| Carbon Tetrachloride | 0.030% |
| Lead | 0.430% |
| Mercury | 0.370% |
| City | Population | Air Quality Index | National Avg. |
| Buhl, MN | 1,111 | 35 | 30.0% |
| Hibbing, MN | 16,417 | 35 | 30.0% |
| McKinley, MN | 135 | 35 | 30.0% |
| Chisholm, MN | 5,025 | 35 | 30.0% |
| Iron Junction, MN | 95 | 35 | 30.0% |
| Mountain Iron, MN | 2,918 | 35 | 30.0% |
| City | Population | Air Quality Index | National Avg. |
| Louisa, KY | 2,918 | 42 | 16.0% |
| Mountville, PA | 2,917 | 45 | 10.0% |
| Peace River E, BC | 2,917 | n/a | |
| Kingston, WA | 2,919 | 45 | 10.0% |
| Cazenovia, NY | 2,920 | 37 | 26.0% |
| Mountain Iron, MN | 2,918 | 35 | 30.0% |