| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 13°F | 30°F | 20°F | 0.7" |
| February | 16°F | 36°F | 24°F | 2.3" |
| March | 30°F | 53°F | 39°F | 6.6" |
| April | 39°F | 62°F | 49°F | 7.4" |
| May | 52°F | 75°F | 62°F | 7.0" |
| June | 63°F | 84°F | 72°F | 22.2" |
| July | 67°F | 88°F | 77°F | 6.3" |
| August | 64°F | 86°F | 73°F | 3.9" |
| September | 56°F | 82°F | 67°F | 4.2" |
| October | 44°F | 67°F | 53°F | 7.3" |
| November | 29°F | 52°F | 38°F | 2.0" |
| December | 14°F | 31°F | 21°F | 2.9" |
| Index | Irene | 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. |
| Gayville, SD | 374 | 35 | 30.0% |
| Davis, SD | 94 | 36 | 28.0% |
| Volin, SD | 171 | 36 | 28.0% |
| Hurley, SD | 416 | 36 | 28.0% |
| Wakonda, SD | 267 | 36 | 28.0% |
| Irene, SD | 549 | 36 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Leslie, AR | 549 | 36 | 28.0% |
| Smelterville, ID | 549 | 43 | 14.0% |
| St. Leonard, MD | 549 | 41 | 18.0% |
| Terry, MT | 549 | 33 | 34.0% |
| Deercroft, NC | 549 | 41 | 18.0% |
| Irene, SD | 549 | 36 | 28.0% |
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