| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 8°F | 29°F | 18°F | 0.6" |
| February | 10°F | 34°F | 21°F | 0.9" |
| March | 24°F | 48°F | 35°F | 1.3" |
| April | 35°F | 62°F | 48°F | 3.0" |
| May | 45°F | 73°F | 59°F | 3.9" |
| June | 57°F | 82°F | 70°F | 5.2" |
| July | 61°F | 87°F | 75°F | 3.2" |
| August | 59°F | 84°F | 71°F | 4.4" |
| September | 51°F | 78°F | 64°F | 3.2" |
| October | 38°F | 64°F | 50°F | 3.1" |
| November | 24°F | 49°F | 36°F | 1.0" |
| December | 11°F | 32°F | 21°F | 1.4" |
| Index | Monroe | South Dakota | National |
| Air quality index | 36 | 36 | 42 |
| Pollution index | 160,795 | 345,623 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 321 |
| Days with moderate air quality | 43 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.003% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Montrose, SD | 551 | 36 | 28.0% |
| Hurley, SD | 416 | 36 | 28.0% |
| Canistota, SD | 663 | 36 | 28.0% |
| Bridgewater, SD | 322 | 36 | 28.0% |
| Marion, SD | 911 | 36 | 28.0% |
| Monroe, SD | 210 | 36 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Cantwell, AK | 210 | 38 | 24.0% |
| Shungnak, AK | 210 | 38 | 24.0% |
| White Hills, AZ | 210 | 54 | 8.0% |
| Monson, CA | 210 | 66 | 32.0% |
| Point Reyes Station, CA | 210 | 34 | 32.0% |
| Monroe, SD | 210 | 36 | 28.0% |
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