| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 7°F | 28°F | 17°F | 0.4" |
| February | 9°F | 31°F | 19°F | 0.8" |
| March | 23°F | 47°F | 33°F | 0.9" |
| April | 33°F | 60°F | 45°F | 1.9" |
| May | 44°F | 71°F | 57°F | 3.3" |
| June | 55°F | 81°F | 67°F | 3.1" |
| July | 61°F | 89°F | 74°F | 2.0" |
| August | 59°F | 86°F | 71°F | 3.0" |
| September | 50°F | 77°F | 62°F | 1.6" |
| October | 37°F | 61°F | 48°F | 1.8" |
| November | 23°F | 46°F | 33°F | 0.4" |
| December | 10°F | 29°F | 19°F | 0.7" |
| Index | Selby | South Dakota | National |
| Air quality index | 20 | 36 | 42 |
| Pollution index | 164,666 | 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. |
| Java, SD | 120 | 20 | 60.0% |
| Lowry, SD | 3 | 20 | 60.0% |
| Glenham, SD | 117 | 20 | 60.0% |
| Akaska, SD | 48 | 20 | 60.0% |
| Selby, SD | 513 | 20 | 60.0% |
| City | Population | Air Quality Index | National Avg. |
| Cedar Creek, AZ | 513 | 44 | 12.0% |
| Walden, CO | 513 | 47 | 6.0% |
| Lewis, IA | 513 | 40 | 20.0% |
| Mayking, KY | 513 | 45 | 10.0% |
| East Hodge, LA | 513 | 34 | 32.0% |
| Selby, SD | 513 | 20 | 60.0% |
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