| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 3°F | 27°F | 14°F | 0.5" |
| February | 5°F | 29°F | 16°F | 0.6" |
| March | 17°F | 45°F | 30°F | 0.7" |
| April | 29°F | 60°F | 43°F | 1.1" |
| May | 39°F | 70°F | 54°F | 2.7" |
| June | 49°F | 80°F | 64°F | 2.6" |
| July | 56°F | 89°F | 72°F | 2.1" |
| August | 53°F | 87°F | 69°F | 1.5" |
| September | 43°F | 77°F | 59°F | 1.6" |
| October | 31°F | 60°F | 44°F | 1.2" |
| November | 18°F | 43°F | 29°F | 0.7" |
| December | 4°F | 27°F | 15°F | 0.8" |
| Index | Williston | 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. |
| Epping, ND | 79 | 34 | 32.0% |
| Springbrook, ND | 14 | 34 | 32.0% |
| Williston, ND | 27,812 | 34 | 32.0% |
| City | Population | Air Quality Index | National Avg. |
| Boisbriand, QC | 27,813 | n/a | |
| Reisterstown, MD | 27,804 | 46 | 8.0% |
| Fridley, MN | 27,789 | 46 | 8.0% |
| Old Bridge, NJ | 27,836 | 41 | 18.0% |
| Slidell, LA | 27,782 | 45 | 10.0% |
| Williston, ND | 27,812 | 34 | 32.0% |
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