| 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 | Gayville | South Dakota | National |
| Air quality index | 35 | 36 | 42 |
| Pollution index | 482,612 | 345,623 | 2,726,193 |
| Measurement | Total |
| Days measured | 364 |
| Days with good air quality | 322 |
| Days with moderate air quality | 42 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| 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% |
| Vermillion, SD | 10,852 | 35 | 30.0% |
| Wynot, NE | 252 | 35 | 30.0% |
| Aten, NE | 21 | 35 | 30.0% |
| Bow Valley, NE | 96 | 35 | 30.0% |
| Gayville, SD | 374 | 35 | 30.0% |
| City | Population | Air Quality Index | National Avg. |
| Potter Valley, CA | 374 | 33 | 34.0% |
| Mondamin, IA | 374 | 40 | 20.0% |
| Eden, ID | 374 | 20 | 60.0% |
| Marshall, IN | 374 | 45 | 10.0% |
| Sylvan Grove, KS | 374 | 32 | 36.0% |
| Gayville, SD | 374 | 35 | 30.0% |
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