| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 20°F | 38°F | 29°F | 2.1" |
| February | 22°F | 41°F | 31°F | 1.9" |
| March | 34°F | 56°F | 44°F | 2.9" |
| April | 44°F | 68°F | 56°F | 4.3" |
| May | 54°F | 77°F | 65°F | 4.5" |
| June | 64°F | 86°F | 74°F | 5.5" |
| July | 66°F | 88°F | 77°F | 4.3" |
| August | 64°F | 86°F | 75°F | 3.2" |
| September | 57°F | 81°F | 68°F | 3.7" |
| October | 46°F | 69°F | 56°F | 3.7" |
| November | 36°F | 55°F | 45°F | 2.5" |
| December | 26°F | 41°F | 33°F | 2.8" |
| Index | Petersburg | Illinois | National |
| Air quality index | 40 | 41 | 42 |
| Pollution index | 400,905 | 3,148,694 | 2,726,193 |
| Measurement | Total |
| Days measured | 360 |
| Days with good air quality | 287 |
| Days with moderate air quality | 73 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Clear Lake, IL | 386 | 40 | 20.0% |
| Mason City, IL | 2,342 | 40 | 20.0% |
| Lake Petersburg, IL | 547 | 40 | 20.0% |
| Cantrall, IL | 104 | 40 | 20.0% |
| Grandview, IL | 1,389 | 40 | 20.0% |
| Petersburg, IL | 2,564 | 40 | 20.0% |
| City | Population | Air Quality Index | National Avg. |
| Premont, TX | 2,564 | 30 | 40.0% |
| Fobes Hill, WA | 2,564 | 45 | 10.0% |
| Cape Neddick, ME | 2,563 | 40 | 20.0% |
| Glenwood, MN | 2,563 | 32 | 36.0% |
| Pembroke, GA | 2,565 | 39 | 22.0% |
| Petersburg, IL | 2,564 | 40 | 20.0% |
Here are the best places to live in Illinois
Most Dangerous States In The US
These are the 10 cheapest cities in Illinois
Check out the 10 most dangerous cities in Illinois