| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 24°F | 41°F | 31°F | 5.3" |
| February | 26°F | 43°F | 33°F | 3.7" |
| March | 38°F | 57°F | 46°F | 4.5" |
| April | 47°F | 69°F | 57°F | 8.3" |
| May | 56°F | 77°F | 66°F | 6.2" |
| June | 65°F | 86°F | 75°F | 8.8" |
| July | 67°F | 88°F | 77°F | 7.5" |
| August | 65°F | 87°F | 75°F | 7.1" |
| September | 58°F | 81°F | 68°F | 8.8" |
| October | 47°F | 70°F | 57°F | 6.4" |
| November | 36°F | 57°F | 45°F | 7.2" |
| December | 29°F | 45°F | 36°F | 5.8" |
| Index | Johnsonville | Illinois | National |
| Air quality index | 43 | 41 | 42 |
| Pollution index | 500,004 | 3,148,694 | 2,726,193 |
| Measurement | Total |
| Days measured | 344 |
| Days with good air quality | 269 |
| Days with moderate air quality | 74 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Clay City, IL | 896 | 40 | 20.0% |
| Flora, IL | 4,686 | 40 | 20.0% |
| Fairfield, IL | 4,912 | 43 | 14.0% |
| Wayne City, IL | 934 | 43 | 14.0% |
| Xenia, IL | 365 | 43 | 14.0% |
| Johnsonville, IL | 50 | 43 | 14.0% |
| City | Population | Air Quality Index | National Avg. |
| Tonopah, AZ | 50 | 74 | 48.0% |
| Fish Camp, CA | 50 | 50 | = 100 |
| Lookout, CA | 50 | 29 | 42.0% |
| Idalia, CO | 50 | 58 | 16.0% |
| Pine Island, FL | 50 | 30 | 40.0% |
| Johnsonville, IL | 50 | 43 | 14.0% |
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