| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 16°F | 35°F | 25°F | 0.1" |
| February | 19°F | 39°F | 27°F | 0.0" |
| March | 30°F | 55°F | 41°F | 0.6" |
| April | 40°F | 65°F | 51°F | 1.9" |
| May | 51°F | 75°F | 62°F | 4.7" |
| June | 62°F | 85°F | 73°F | 2.6" |
| July | 65°F | 87°F | 76°F | 2.0" |
| August | 63°F | 84°F | 73°F | 3.0" |
| September | 54°F | 79°F | 65°F | 2.1" |
| October | 42°F | 66°F | 52°F | 1.4" |
| November | 29°F | 53°F | 39°F | 0.7" |
| December | 18°F | 37°F | 26°F | 0.5" |
| Index | Grafton | Nebraska | National |
| Air quality index | 19 | 86 | 42 |
| Pollution index | 214,983 | 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 | 0.004% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.001% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Geneva, NE | 1,955 | 19 | 62.0% |
| Fairmont, NE | 750 | 19 | 62.0% |
| McCool Junction, NE | 559 | 19 | 62.0% |
| Henderson, NE | 946 | 19 | 62.0% |
| Saronville, NE | 58 | 19 | 62.0% |
| Grafton, NE | 146 | 19 | 62.0% |
| City | Population | Air Quality Index | National Avg. |
| Chinese Camp, CA | 146 | 39 | 22.0% |
| Sharpsburg, IA | 146 | 43 | 14.0% |
| Harmon, IL | 146 | 42 | 16.0% |
| Hettick, IL | 146 | 40 | 20.0% |
| Stoy, IL | 146 | 36 | 28.0% |
| Grafton, NE | 146 | 19 | 62.0% |
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