| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 12°F | 40°F | 25°F | 0.3" |
| February | 13°F | 43°F | 26°F | 0.5" |
| March | 23°F | 55°F | 37°F | 0.8" |
| April | 31°F | 61°F | 45°F | 2.1" |
| May | 40°F | 70°F | 54°F | 3.5" |
| June | 51°F | 82°F | 66°F | 3.2" |
| July | 58°F | 92°F | 74°F | 1.8" |
| August | 55°F | 89°F | 71°F | 2.2" |
| September | 46°F | 81°F | 62°F | 1.3" |
| October | 34°F | 65°F | 48°F | 1.2" |
| November | 22°F | 53°F | 36°F | 0.5" |
| December | 11°F | 38°F | 23°F | 0.6" |
| Index | New Underwood | South Dakota | National |
| Air quality index | 44 | 36 | 42 |
| Pollution index | 551,228 | 345,623 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 274 |
| Days with moderate air quality | 87 |
| Days w/ poor A.Q. for sensitive groups | 4 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.010% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Green Valley, SD | 1,290 | 44 | 12.0% |
| Ashland Heights, SD | 1,118 | 44 | 12.0% |
| Rapid Valley, SD | 8,750 | 44 | 12.0% |
| Box Elder, SD | 10,205 | 44 | 12.0% |
| Caputa, SD | 0 | 44 | 12.0% |
| New Underwood, SD | 779 | 44 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| Hickman, CA | 779 | 49 | 2.0% |
| Doerun, GA | 779 | 40 | 20.0% |
| Colo, IA | 779 | 37 | 26.0% |
| Dighton, KS | 779 | 15 | 70.0% |
| Garrison, KY | 779 | 14 | 72.0% |
| New Underwood, SD | 779 | 44 | 12.0% |