| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 1°F | 22°F | 11°F | 0.9" |
| February | 3°F | 24°F | 13°F | 0.6" |
| March | 18°F | 40°F | 29°F | 1.0" |
| April | 32°F | 58°F | 45°F | 1.7" |
| May | 44°F | 72°F | 57°F | 3.3" |
| June | 55°F | 81°F | 68°F | 4.6" |
| July | 59°F | 86°F | 73°F | 2.6" |
| August | 56°F | 83°F | 69°F | 3.0" |
| September | 48°F | 76°F | 61°F | 3.1" |
| October | 37°F | 61°F | 47°F | 2.4" |
| November | 22°F | 44°F | 32°F | 0.7" |
| December | 6°F | 26°F | 16°F | 1.1" |
| Index | Hillsboro | North Dakota | National |
| Air quality index | 33 | 35 | 42 |
| Pollution index | 151,183 | 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 | 0.002% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Nielsville, MN | 93 | 33 | 34.0% |
| Grandin, ND | 135 | 33 | 34.0% |
| Portland, ND | 666 | 33 | 34.0% |
| Climax, MN | 218 | 33 | 34.0% |
| Shelly, MN | 164 | 33 | 34.0% |
| Hillsboro, ND | 1,627 | 33 | 34.0% |
| City | Population | Air Quality Index | National Avg. |
| Northampton, NY | 1,627 | 41 | 18.0% |
| Upper Brookville, NY | 1,627 | 51 | 2.0% |
| Powhatan Point, OH | 1,627 | 39 | 22.0% |
| Latta, SC | 1,627 | 40 | 20.0% |
| Johnson, VT | 1,627 | 37 | 26.0% |
| Hillsboro, ND | 1,627 | 33 | 34.0% |
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