| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 8°F | 26°F | 17°F | 0.6" |
| February | 11°F | 30°F | 19°F | 1.1" |
| March | 25°F | 44°F | 33°F | 3.2" |
| April | 35°F | 58°F | 46°F | 3.1" |
| May | 48°F | 71°F | 59°F | 5.0" |
| June | 58°F | 80°F | 69°F | 6.7" |
| July | 62°F | 86°F | 74°F | 5.7" |
| August | 60°F | 82°F | 70°F | 7.1" |
| September | 52°F | 77°F | 63°F | 6.5" |
| October | 40°F | 61°F | 50°F | 5.0" |
| November | 27°F | 47°F | 36°F | 3.1" |
| December | 13°F | 29°F | 21°F | 1.8" |
| Index | Altamont | South Dakota | National |
| Air quality index | 25 | 36 | 42 |
| Pollution index | 580,913 | 345,623 | 2,726,193 |
| Measurement | Total |
| Days measured | 361 |
| Days with good air quality | 325 |
| Days with moderate air quality | 36 |
| 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 | 0.002% |
| Lead | 0.004% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Clear Lake, SD | 1,503 | 25 | 50.0% |
| Kranzburg, SD | 199 | 25 | 50.0% |
| Gary, SD | 284 | 25 | 50.0% |
| Goodwin, SD | 102 | 25 | 50.0% |
| Waverly, SD | 51 | 25 | 50.0% |
| Altamont, SD | 30 | 25 | 50.0% |
| City | Population | Air Quality Index | National Avg. |
| Alatna, AK | 30 | 38 | 24.0% |
| Skwentna, AK | 30 | 31 | 38.0% |
| Fourche, AR | 30 | 45 | 10.0% |
| Hidden Lake, CO | 30 | 47 | 6.0% |
| Gibson, IA | 30 | 35 | 30.0% |
| Altamont, SD | 30 | 25 | 50.0% |
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