| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 33°F | 52°F | 42°F | 5.9" |
| February | 37°F | 55°F | 47°F | 2.2" |
| March | 49°F | 68°F | 59°F | 14.4" |
| April | 52°F | 71°F | 63°F | 4.9" |
| May | 63°F | 79°F | 72°F | 11.9" |
| June | 70°F | 88°F | 80°F | 13.6" |
| July | 73°F | 91°F | 83°F | 7.2" |
| August | 74°F | 94°F | 86°F | 18.1" |
| September | 67°F | 87°F | 79°F | 5.9" |
| October | 54°F | 76°F | 66°F | 4.9" |
| November | 43°F | 68°F | 55°F | 1.6" |
| December | 31°F | 52°F | 41°F | 4.4" |
| Index | Duncan | Oklahoma | National |
| Air quality index | 43 | 55 | 42 |
| Pollution index | 906,693 | 1,271,533 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 285 |
| Days with moderate air quality | 80 |
| 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 | 0.002% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Comanche, OK | 1,896 | 43 | 14.0% |
| Bray, OK | 1,053 | 43 | 14.0% |
| Empire City, OK | 830 | 43 | 14.0% |
| Central High, OK | 1,507 | 43 | 14.0% |
| Meridian town, OK | 36 | 43 | 14.0% |
| Duncan, OK | 22,529 | 43 | 14.0% |
| City | Population | Air Quality Index | National Avg. |
| South Lake Tahoe, CA | 22,535 | 13 | 74.0% |
| Hopewell, VA | 22,500 | 44 | 12.0% |
| Greenfield, IN | 22,561 | 54 | 8.0% |
| Silver Firs, WA | 22,564 | 45 | 10.0% |
| Dolton, IL | 22,487 | 55 | 10.0% |
| Duncan, OK | 22,529 | 43 | 14.0% |
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