| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 24°F | 41°F | 31°F | 3.4" |
| February | 25°F | 43°F | 33°F | 3.7" |
| March | 38°F | 57°F | 46°F | 3.1" |
| April | 47°F | 68°F | 56°F | 6.6" |
| May | 56°F | 76°F | 65°F | 6.1" |
| June | 65°F | 85°F | 75°F | 3.5" |
| July | 67°F | 87°F | 77°F | 7.3" |
| August | 66°F | 86°F | 75°F | 6.8" |
| September | 58°F | 80°F | 68°F | 4.4" |
| October | 47°F | 68°F | 57°F | 6.7" |
| November | 36°F | 56°F | 45°F | 4.9" |
| December | 28°F | 43°F | 35°F | 6.3" |
| Index | Edwardsville | Illinois | National |
| Air quality index | 54 | 41 | 50 |
| Pollution index | 6,055,640 | 3,148,694 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 134 |
| Days with moderate air quality | 221 |
| Days w/ poor A.Q. for sensitive groups | 8 |
| Days with unhealthy air quality | 2 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.070% |
| Carbon Tetrachloride | 0.040% |
| Lead | 0.100% |
| Mercury | 0.230% |
| City | Population | Air Quality Index | National Avg. |
| Williamson, IL | 233 | 54 | 8.0% |
| Alton, IL | 27,175 | 54 | 8.0% |
| Hamel, IL | 1,015 | 54 | 8.0% |
| Mitchell, IL | 1,183 | 54 | 8.0% |
| South Roxana, IL | 2,316 | 54 | 8.0% |
| Edwardsville, IL | 25,044 | 54 | 8.0% |
| City | Population | Air Quality Index | National Avg. |
| Balch Springs, TX | 25,043 | 51 | 2.0% |
| Riverside, OH | 25,036 | 47 | 6.0% |
| Ardmore, OK | 25,027 | 43 | 14.0% |
| Mint Hill, NC | 25,024 | 49 | 2.0% |
| Canton, GA | 25,022 | 52 | 4.0% |
| Edwardsville, IL | 25,044 | 54 | 8.0% |
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