| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 14°F | 30°F | 22°F | 2.3" |
| February | 14°F | 31°F | 23°F | 2.8" |
| March | 26°F | 45°F | 35°F | 3.7" |
| April | 36°F | 58°F | 46°F | 5.9" |
| May | 46°F | 71°F | 58°F | 4.8" |
| June | 56°F | 79°F | 67°F | 7.8" |
| July | 59°F | 82°F | 70°F | 11.4" |
| August | 57°F | 81°F | 68°F | 5.4" |
| September | 50°F | 74°F | 61°F | 7.1" |
| October | 40°F | 61°F | 50°F | 5.8" |
| November | 29°F | 48°F | 38°F | 5.2" |
| December | 19°F | 34°F | 27°F | 3.3" |
| Index | Darien | Wisconsin | National |
| Air quality index | 38 | 69 | 42 |
| Pollution index | 151,096 | 2,842,418 | 2,726,193 |
| Measurement | Total |
| Days measured | 203 |
| Days with good air quality | 185 |
| Days with moderate air quality | 18 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.000% |
| Benzene | 0.002% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.010% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Elkhorn, WI | 10,034 | 37 | 26.0% |
| Delavan, WI | 8,296 | 37 | 26.0% |
| Lauderdale Lakes, WI | 1,437 | 37 | 26.0% |
| Hebron, IL | 1,730 | 37 | 26.0% |
| Williams Bay, WI | 2,607 | 37 | 26.0% |
| Darien, WI | 1,471 | 38 | 24.0% |
| City | Population | Air Quality Index | National Avg. |
| Urania, LA | 1,471 | 30 | 40.0% |
| Bloomfield, NY | 1,471 | 37 | 26.0% |
| Deloraine-Winchester, MB | 1,471 | n/a | |
| Clarendon, AR | 1,470 | 45 | 10.0% |
| Belleair Beach, FL | 1,472 | 43 | 14.0% |
| Darien, WI | 1,471 | 38 | 24.0% |
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