| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 12°F | 31°F | 20°F | 1.2" |
| February | 15°F | 34°F | 24°F | 1.8" |
| March | 28°F | 53°F | 39°F | 4.1" |
| April | 37°F | 60°F | 47°F | 5.0" |
| May | 48°F | 71°F | 59°F | 7.2" |
| June | 60°F | 82°F | 70°F | 10.6" |
| July | 65°F | 93°F | 78°F | 2.1" |
| August | 63°F | 87°F | 74°F | 9.0" |
| September | 56°F | 83°F | 67°F | 6.8" |
| October | 41°F | 66°F | 51°F | 8.6" |
| November | 28°F | 51°F | 37°F | 2.5" |
| December | 13°F | 31°F | 22°F | 1.3" |
| Index | Reliance | South Dakota | National |
| Air quality index | 20 | 36 | 42 |
| Pollution index | 385,481 | 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 | 0.010% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Fort Thompson, SD | 1,275 | 20 | 60.0% |
| Kennebec, SD | 344 | 20 | 60.0% |
| Lower Brule, SD | 971 | 20 | 60.0% |
| Chamberlain, SD | 2,549 | 20 | 60.0% |
| Oacoma, SD | 375 | 20 | 60.0% |
| Reliance, SD | 109 | 20 | 60.0% |
| City | Population | Air Quality Index | National Avg. |
| Eagle, AK | 109 | 38 | 24.0% |
| Mud Bay, AK | 109 | 20 | 60.0% |
| Standing Rock, AL | 109 | 42 | 16.0% |
| Kohls Ranch, AZ | 109 | 60 | 20.0% |
| Vilas, CO | 109 | 20 | 60.0% |
| Reliance, SD | 109 | 20 | 60.0% |
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