| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 14°F | 35°F | 24°F | 1.2" |
| February | 17°F | 39°F | 26°F | 1.4" |
| March | 29°F | 54°F | 40°F | 5.7" |
| April | 39°F | 64°F | 50°F | 5.3" |
| May | 50°F | 75°F | 61°F | 8.2" |
| June | 61°F | 85°F | 72°F | 8.5" |
| July | 65°F | 88°F | 76°F | 6.0" |
| August | 62°F | 84°F | 72°F | 6.4" |
| September | 54°F | 79°F | 65°F | 4.7" |
| October | 40°F | 65°F | 51°F | 6.4" |
| November | 28°F | 52°F | 39°F | 2.2" |
| December | 16°F | 36°F | 25°F | 2.7" |
| Index | Duncan | Nebraska | National |
| Air quality index | 19 | 86 | 42 |
| Pollution index | 222,362 | 590,627 | 2,726,193 |
| Measurement | Total |
| Days measured | 97 |
| Days with good air quality | 92 |
| Days with moderate air quality | 5 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.003% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Silver Creek, NE | 490 | 19 | 62.0% |
| Osceola, NE | 826 | 19 | 62.0% |
| Genoa, NE | 905 | 19 | 62.0% |
| Platte Center, NE | 378 | 19 | 62.0% |
| Monroe, NE | 299 | 19 | 62.0% |
| Duncan, NE | 487 | 19 | 62.0% |
| City | Population | Air Quality Index | National Avg. |
| Arkansas City, AR | 487 | 43 | 14.0% |
| Smartsville, CA | 487 | 44 | 12.0% |
| Yettem, CA | 487 | 66 | 32.0% |
| Downieville-Lawson-Dumont, CO | 487 | 47 | 6.0% |
| Lyerly, GA | 487 | 40 | 20.0% |
| Duncan, NE | 487 | 19 | 62.0% |
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