| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 8°F | 28°F | 18°F | 1.0" |
| February | 9°F | 30°F | 20°F | 0.6" |
| March | 24°F | 46°F | 34°F | 1.5" |
| April | 34°F | 59°F | 46°F | 3.7" |
| May | 44°F | 71°F | 57°F | 4.5" |
| June | 54°F | 80°F | 67°F | 5.6" |
| July | 57°F | 84°F | 71°F | 6.2" |
| August | 56°F | 81°F | 68°F | 4.8" |
| September | 48°F | 74°F | 60°F | 5.4" |
| October | 37°F | 61°F | 48°F | 3.4" |
| November | 27°F | 46°F | 36°F | 1.5" |
| December | 14°F | 32°F | 23°F | 2.3" |
| Index | Sparta | Wisconsin | National |
| Air quality index | 35 | 69 | 42 |
| Pollution index | 3,548,710 | 2,842,418 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 310 |
| Days with moderate air quality | 55 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.050% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.010% |
| Mercury | 0.020% |
| City | Population | Air Quality Index | National Avg. |
| Cashton, WI | 961 | 35 | 30.0% |
| Melrose, WI | 474 | 35 | 30.0% |
| Rockland, WI | 595 | 35 | 30.0% |
| Wilton, WI | 542 | 35 | 30.0% |
| Bangor, WI | 1,214 | 35 | 30.0% |
| Sparta, WI | 9,751 | 35 | 30.0% |
| City | Population | Air Quality Index | National Avg. |
| Oil City, PA | 9,750 | 9 | 82.0% |
| San Diego Country Estates, CA | 9,752 | 64 | 28.0% |
| Ellisville, MO | 9,752 | 54 | 8.0% |
| Eunice, LA | 9,754 | 41 | 18.0% |
| New Hyde Park, NY | 9,746 | 51 | 2.0% |
| Sparta, WI | 9,751 | 35 | 30.0% |
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