| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 6°F | 27°F | 15°F | 0.6" |
| February | 10°F | 31°F | 19°F | 0.9" |
| March | 27°F | 51°F | 36°F | 2.8" |
| April | 35°F | 60°F | 46°F | 3.6" |
| May | 47°F | 72°F | 58°F | 6.9" |
| June | 58°F | 81°F | 68°F | 3.9" |
| July | 63°F | 93°F | 76°F | 1.9" |
| August | 59°F | 88°F | 71°F | 6.5" |
| September | 52°F | 81°F | 63°F | 2.5" |
| October | 39°F | 64°F | 48°F | 4.8" |
| November | 24°F | 48°F | 34°F | 0.4" |
| December | 11°F | 31°F | 20°F | 1.9" |
| Index | Eureka | South Dakota | National |
| Air quality index | 20 | 36 | 42 |
| Pollution index | 108,405 | 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 | 0.001% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Hillsview, SD | 0 | 20 | 60.0% |
| Hosmer, SD | 227 | 20 | 60.0% |
| Artas, SD | 34 | 20 | 60.0% |
| Zeeland, ND | 84 | 36 | 28.0% |
| Eureka, SD | 992 | 20 | 60.0% |
| City | Population | Air Quality Index | National Avg. |
| Rossville, KS | 992 | 41 | 18.0% |
| Stamping Ground, KY | 992 | 42 | 16.0% |
| Mackinac Island, MI | 992 | 32 | 36.0% |
| Alexandria, TN | 992 | 25 | 50.0% |
| Allardt, TN | 992 | 53 | 6.0% |
| Eureka, SD | 992 | 20 | 60.0% |
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