| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 18°F | 33°F | 25°F | 4.0" |
| February | 13°F | 30°F | 22°F | 3.3" |
| March | 25°F | 45°F | 35°F | 3.0" |
| April | 35°F | 60°F | 48°F | 2.7" |
| May | 43°F | 71°F | 57°F | 3.9" |
| June | 55°F | 83°F | 70°F | 5.1" |
| July | 56°F | 83°F | 71°F | 4.4" |
| August | 59°F | 83°F | 71°F | 3.9" |
| September | 49°F | 78°F | 63°F | 1.9" |
| October | 42°F | 66°F | 54°F | 2.3" |
| November | 28°F | 49°F | 39°F | 5.0" |
| December | 19°F | 32°F | 26°F | 3.5" |
| Index | Knollwood | Illinois | National |
| Air quality index | 39 | 41 | 42 |
| Pollution index | 543,516 | 3,148,694 | 2,726,193 |
| Measurement | Total |
| Days measured | 203 |
| Days with good air quality | 174 |
| Days with moderate air quality | 28 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.004% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.000% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Round Lake, IL | 18,235 | 39 | 22.0% |
| Antioch, IL | 14,231 | 39 | 22.0% |
| Grandwood Park, IL | 5,114 | 39 | 22.0% |
| Mundelein, IL | 31,574 | 39 | 22.0% |
| Venetian Village, IL | 2,561 | 39 | 22.0% |
| Knollwood, IL | 1,684 | 39 | 22.0% |
| City | Population | Air Quality Index | National Avg. |
| Rouse, CA | 1,684 | 49 | 2.0% |
| Princeville, IL | 1,684 | 41 | 18.0% |
| Cassopolis, MI | 1,684 | 39 | 22.0% |
| East Helena, MT | 1,684 | 40 | 20.0% |
| Sturgeon Lake 154, AB | 1,684 | n/a | |
| Knollwood, IL | 1,684 | 39 | 22.0% |
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