| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 35°F | 59°F | 46°F | 4.2" |
| February | 40°F | 64°F | 51°F | 2.8" |
| March | 41°F | 73°F | 57°F | 3.9" |
| April | 47°F | 83°F | 65°F | 2.8" |
| May | 58°F | 93°F | 76°F | 0.3" |
| June | 66°F | 101°F | 85°F | 0.7" |
| July | 73°F | 103°F | 87°F | 2.4" |
| August | 72°F | 98°F | 84°F | 2.7" |
| September | 65°F | 96°F | 81°F | 0.3" |
| October | 54°F | 86°F | 69°F | 2.6" |
| November | 43°F | 75°F | 58°F | 1.6" |
| December | 31°F | 62°F | 46°F | 1.9" |
| Index | Duncan | Arizona | National |
| Air quality index | 37 | 57 | 42 |
| Pollution index | 902,435 | 9,766,019 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 362 |
| Days with moderate air quality | 3 |
| Days w/ poor A.Q. for sensitive groups | |
| Days with unhealthy air quality |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.380% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Virden, NM | 174 | 37 | 26.0% |
| Franklin, AZ | 75 | 37 | 26.0% |
| York, AZ | 630 | 37 | 26.0% |
| Duncan, AZ | 712 | 37 | 26.0% |
| City | Population | Air Quality Index | National Avg. |
| Frankford, DE | 712 | 36 | 28.0% |
| Medaryville, IN | 712 | 37 | 26.0% |
| Littlefork, MN | 712 | 35 | 30.0% |
| Dunkirk, OH | 712 | 39 | 22.0% |
| Driscoll, TX | 712 | 30 | 40.0% |
| Duncan, AZ | 712 | 37 | 26.0% |
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