| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 17°F | 38°F | 26°F | 1.6" |
| February | 20°F | 42°F | 29°F | 1.8" |
| March | 32°F | 57°F | 43°F | 3.6" |
| April | 42°F | 66°F | 53°F | 6.1" |
| May | 52°F | 76°F | 63°F | 6.3" |
| June | 63°F | 86°F | 74°F | 6.4" |
| July | 67°F | 90°F | 78°F | 5.4" |
| August | 64°F | 87°F | 75°F | 7.7" |
| September | 55°F | 80°F | 67°F | 9.2" |
| October | 43°F | 68°F | 54°F | 6.4" |
| November | 31°F | 55°F | 41°F | 4.1" |
| December | 20°F | 40°F | 28°F | 4.1" |
| Index | Cortland | Nebraska | National |
| Air quality index | 31 | 86 | 42 |
| Pollution index | 648,221 | 590,627 | 2,726,193 |
| Measurement | Total |
| Days measured | 360 |
| Days with good air quality | 338 |
| Days with moderate air quality | 22 |
| 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 | 0.002% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Adams, NE | 556 | 31 | 38.0% |
| Hallam, NE | 236 | 31 | 38.0% |
| Hickman, NE | 2,432 | 31 | 38.0% |
| Roca, NE | 130 | 31 | 38.0% |
| Clatonia, NE | 384 | 31 | 38.0% |
| Cortland, NE | 550 | 31 | 38.0% |
| City | Population | Air Quality Index | National Avg. |
| Eek, AK | 550 | 31 | 38.0% |
| New Cuyama, CA | 550 | 44 | 12.0% |
| San Simeon, CA | 550 | 46 | 8.0% |
| Camargo, IL | 550 | 42 | 16.0% |
| Thebes, IL | 550 | 44 | 12.0% |
| Cortland, NE | 550 | 31 | 38.0% |
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