| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 3°F | 20°F | 12°F | 1.4" |
| February | 3°F | 22°F | 13°F | 3.7" |
| March | 15°F | 35°F | 25°F | 5.3" |
| April | 28°F | 50°F | 40°F | 1.0" |
| May | 41°F | 63°F | 52°F | 2.6" |
| June | 51°F | 72°F | 62°F | 3.5" |
| July | 56°F | 77°F | 67°F | 2.5" |
| August | 53°F | 77°F | 66°F | 1.5" |
| September | 44°F | 68°F | 57°F | 2.6" |
| October | 33°F | 53°F | 42°F | 1.1" |
| November | 18°F | 35°F | 26°F | 1.9" |
| December | 6°F | 22°F | 14°F | 2.5" |
| Index | Fortuna | North Dakota | National |
| Air quality index | 34 | 35 | 42 |
| Pollution index | 563,599 | 1,038,665 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 309 |
| Days with moderate air quality | 53 |
| Days w/ poor A.Q. for sensitive groups | 3 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.010% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Westby, MT | 163 | 34 | 32.0% |
| Ambrose, ND | 11 | 34 | 32.0% |
| Fortuna, ND | 34 | 34 | 32.0% |
| City | Population | Air Quality Index | National Avg. |
| Amado, AZ | 34 | 31 | 38.0% |
| Cotopaxi, CO | 34 | 16 | 68.0% |
| Dixonville, FL | 34 | 41 | 18.0% |
| Indian Creek, FL | 34 | 41 | 18.0% |
| Gray, IA | 34 | 40 | 20.0% |
| Fortuna, ND | 34 | 34 | 32.0% |
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