| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 3°F | 25°F | 11°F | 0.2" |
| February | 7°F | 26°F | 14°F | 0.5" |
| March | 22°F | 41°F | 30°F | 1.0" |
| April | 35°F | 58°F | 46°F | 3.8" |
| May | 48°F | 71°F | 58°F | 4.0" |
| June | 60°F | 81°F | 70°F | 5.6" |
| July | 62°F | 86°F | 73°F | 0.3" |
| August | 58°F | 81°F | 67°F | 3.5" |
| September | 52°F | 77°F | 62°F | 3.9" |
| October | 40°F | 62°F | 49°F | 1.6" |
| November | 24°F | 43°F | 31°F | 1.1" |
| December | 7°F | 24°F | 14°F | 0.6" |
| Index | Harrold | South Dakota | National |
| Air quality index | 20 | 36 | 42 |
| Pollution index | 201,985 | 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 | 0.002% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Blunt, SD | 383 | 20 | 60.0% |
| Highmore, SD | 832 | 20 | 60.0% |
| Harrold, SD | 110 | 20 | 60.0% |
| City | Population | Air Quality Index | National Avg. |
| Naukati Bay, AK | 110 | 20 | 60.0% |
| Lower Santan Village, AZ | 110 | 74 | 48.0% |
| Talking Rock, GA | 110 | 43 | 14.0% |
| Masonville, IA | 110 | 39 | 22.0% |
| Media, IL | 110 | 29 | 42.0% |
| Harrold, SD | 110 | 20 | 60.0% |
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