| 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. |
| 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% |
| Silver Creek, NE | 490 | 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% |
Here are the best places to live in Nebraska
See the best places to live in Duncan
Most Dangerous Cities In The US
Check out the 10 most dangerous cities in Nebraska