| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 14°F | 31°F | 22°F | 2.9" |
| February | 18°F | 35°F | 26°F | 1.6" |
| March | 30°F | 49°F | 38°F | 2.6" |
| April | 38°F | 61°F | 48°F | 5.8" |
| May | 50°F | 74°F | 61°F | 5.4" |
| June | 59°F | 83°F | 71°F | 6.3" |
| July | 66°F | 90°F | 78°F | 3.9" |
| August | 61°F | 85°F | 72°F | 5.2" |
| September | 51°F | 74°F | 62°F | 2.8" |
| October | 40°F | 63°F | 51°F | 8.9" |
| November | 33°F | 51°F | 41°F | 2.9" |
| December | 20°F | 35°F | 27°F | 3.2" |
| Index | Middleton | Wisconsin | National |
| Air quality index | 39 | 69 | 42 |
| Pollution index | 1,728,820 | 2,842,418 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 285 |
| Days with moderate air quality | 80 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.003% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.001% |
| Mercury | 0.002% |
| City | Population | Air Quality Index | National Avg. |
| Sauk City, WI | 3,557 | 35 | 30.0% |
| Lodi, WI | 3,180 | 35 | 30.0% |
| Prairie du Sac, WI | 4,557 | 35 | 30.0% |
| DeForest, WI | 10,758 | 39 | 22.0% |
| Maple Bluff, WI | 1,323 | 39 | 22.0% |
| Middleton, WI | 20,512 | 39 | 22.0% |
| City | Population | Air Quality Index | National Avg. |
| Glassboro, NJ | 20,509 | 40 | 20.0% |
| Rosedale, MD | 20,525 | 46 | 8.0% |
| Parma Heights, OH | 20,527 | 50 | = 100 |
| South Frontenac, ON | 20,491 | n/a | |
| East Northport, NY | 20,490 | 43 | 14.0% |
| Middleton, WI | 20,512 | 39 | 22.0% |