| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 8°F | 29°F | 18°F | 0.6" |
| February | 10°F | 34°F | 21°F | 0.9" |
| March | 24°F | 48°F | 35°F | 1.3" |
| April | 35°F | 62°F | 48°F | 3.0" |
| May | 45°F | 73°F | 59°F | 3.9" |
| June | 57°F | 82°F | 70°F | 5.2" |
| July | 61°F | 87°F | 75°F | 3.2" |
| August | 59°F | 84°F | 71°F | 4.4" |
| September | 51°F | 78°F | 64°F | 3.2" |
| October | 38°F | 64°F | 50°F | 3.1" |
| November | 24°F | 49°F | 36°F | 1.0" |
| December | 11°F | 32°F | 21°F | 1.4" |
| Index | Hartford | South Dakota | National |
| Air quality index | 36 | 36 | 42 |
| Pollution index | 2,464,570 | 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 | 0.030% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.020% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Dell Rapids, SD | 3,678 | 36 | 28.0% |
| Harrisburg, SD | 6,420 | 36 | 28.0% |
| Monroe, SD | 210 | 36 | 28.0% |
| Meadow View Addition, SD | 632 | 36 | 28.0% |
| Tea, SD | 5,714 | 36 | 28.0% |
| Hartford, SD | 3,300 | 36 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Heron Bay, GA | 3,300 | 52 | 4.0% |
| Water Valley, MS | 3,300 | 33 | 34.0% |
| Elma, WA | 3,299 | 20 | 60.0% |
| Pagedale, MO | 3,301 | 54 | 8.0% |
| Southampton, NY | 3,301 | 41 | 18.0% |
| Hartford, SD | 3,300 | 36 | 28.0% |
Here are the best places to live in South Dakota
See the best places to live in Hartford
Check out the 10 most dangerous cities in South Dakota
These are the largest cities in South Dakota