| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 16°F | 38°F | 26°F | 0.8" |
| February | 17°F | 39°F | 27°F | 0.8" |
| March | 28°F | 53°F | 38°F | 2.1" |
| April | 36°F | 61°F | 47°F | 5.2" |
| May | 46°F | 71°F | 57°F | 6.4" |
| June | 57°F | 82°F | 69°F | 6.7" |
| July | 63°F | 89°F | 75°F | 5.1" |
| August | 60°F | 85°F | 71°F | 6.1" |
| September | 51°F | 78°F | 63°F | 4.4" |
| October | 39°F | 64°F | 49°F | 4.0" |
| November | 27°F | 52°F | 37°F | 2.0" |
| December | 16°F | 36°F | 25°F | 1.1" |
| Index | Johnstown | Nebraska | National |
| Air quality index | 19 | 86 | 42 |
| Pollution index | 132,424 | 590,627 | 2,726,193 |
| Measurement | Total |
| Days measured | 60 |
| Days with good air quality | 55 |
| Days with moderate air quality | 5 |
| Days w/ poor A.Q. for sensitive groups | |
| Days with unhealthy air quality |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.002% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.005% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Ainsworth, NE | 1,655 | 19 | 62.0% |
| Wood Lake, NE | 26 | 19 | 62.0% |
| Johnstown, NE | 36 | 19 | 62.0% |
| City | Population | Air Quality Index | National Avg. |
| Excursion Inlet, AK | 36 | 20 | 60.0% |
| Proberta, CA | 36 | 41 | 18.0% |
| Maybell, CO | 36 | 49 | 2.0% |
| Coburg, IA | 36 | 40 | 20.0% |
| St. Vincent, MN | 36 | 33 | 34.0% |
| Johnstown, NE | 36 | 19 | 62.0% |
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