| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 13°F | 32°F | 21°F | 0.9" |
| February | 15°F | 35°F | 23°F | 1.8" |
| March | 28°F | 50°F | 37°F | 2.8" |
| April | 38°F | 62°F | 49°F | 6.1" |
| May | 49°F | 73°F | 60°F | 4.3" |
| June | 60°F | 83°F | 71°F | 6.2" |
| July | 65°F | 87°F | 76°F | 6.5" |
| August | 62°F | 83°F | 72°F | 6.6" |
| September | 53°F | 77°F | 64°F | 5.9" |
| October | 41°F | 64°F | 51°F | 7.9" |
| November | 28°F | 49°F | 37°F | 1.6" |
| December | 15°F | 33°F | 23°F | 2.2" |
| Index | Yankton | South Dakota | National |
| Air quality index | 36 | 36 | 42 |
| Pollution index | 482,612 | 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 | 0.010% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.004% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| St. Helena, NE | 94 | 35 | 30.0% |
| Bow Valley, NE | 96 | 35 | 30.0% |
| Wynot, NE | 252 | 35 | 30.0% |
| Crofton, NE | 898 | 35 | 30.0% |
| Gayville, SD | 374 | 35 | 30.0% |
| Yankton, SD | 14,619 | 36 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Greenlawn, NY | 14,598 | 43 | 14.0% |
| Ferndale, WA | 14,591 | 34 | 32.0% |
| Sharonville, OH | 14,659 | 54 | 8.0% |
| Scottsbluff, NE | 14,660 | 19 | 62.0% |
| Groveton, VA | 14,664 | 47 | 6.0% |
| Yankton, SD | 14,619 | 36 | 28.0% |
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