| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 6°F | 28°F | 17°F | 0.5" |
| February | 9°F | 34°F | 20°F | 0.7" |
| March | 22°F | 48°F | 34°F | 1.0" |
| April | 33°F | 62°F | 47°F | 2.2" |
| May | 44°F | 73°F | 58°F | 3.2" |
| June | 55°F | 83°F | 69°F | 4.5" |
| July | 61°F | 89°F | 75°F | 2.7" |
| August | 58°F | 85°F | 71°F | 3.3" |
| September | 49°F | 79°F | 63°F | 2.8" |
| October | 36°F | 64°F | 49°F | 2.2" |
| November | 22°F | 49°F | 34°F | 0.8" |
| December | 9°F | 31°F | 19°F | 1.3" |
| Index | Frankfort | South Dakota | National |
| Air quality index | 20 | 36 | 42 |
| Pollution index | 206,038 | 345,623 | 2,726,193 |
| Measurement | Total |
| Days measured | 122 |
| Days with good air quality | 112 |
| Days with moderate air quality | 10 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.003% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Ashton, SD | 91 | 20 | 60.0% |
| Turton, SD | 54 | 20 | 60.0% |
| Redfield, SD | 2,496 | 20 | 60.0% |
| Tulare, SD | 254 | 20 | 60.0% |
| Doland, SD | 288 | 20 | 60.0% |
| Frankfort, SD | 139 | 20 | 60.0% |
| City | Population | Air Quality Index | National Avg. |
| Fisher, AR | 139 | 45 | 10.0% |
| East Shore, CA | 139 | 46 | 8.0% |
| Greenview, CA | 139 | 36 | 28.0% |
| Mackey, IN | 139 | 45 | 10.0% |
| Lorraine, KS | 139 | 40 | 20.0% |
| Frankfort, SD | 139 | 20 | 60.0% |
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