| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 8°F | 24°F | 15°F | 1.0" |
| February | 9°F | 27°F | 17°F | 2.9" |
| March | 24°F | 42°F | 32°F | 2.6" |
| April | 37°F | 57°F | 46°F | 5.5" |
| May | 48°F | 70°F | 58°F | 6.3" |
| June | 59°F | 79°F | 68°F | 6.1" |
| July | 63°F | 83°F | 73°F | 6.3" |
| August | 61°F | 80°F | 70°F | 8.3" |
| September | 53°F | 73°F | 62°F | 6.4" |
| October | 40°F | 58°F | 48°F | 5.0" |
| November | 27°F | 43°F | 35°F | 2.4" |
| December | 13°F | 27°F | 19°F | 2.0" |
| Index | Watertown | Minnesota | National |
| Air quality index | 46 | 35 | 42 |
| Pollution index | 1,774,860 | 1,854,519 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 214 |
| Days with moderate air quality | 148 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality | 1 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.001% |
| Lead | 0.003% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Howard Lake, MN | 1,897 | 32 | 36.0% |
| Waverly, MN | 1,513 | 32 | 36.0% |
| Mayer, MN | 2,313 | 46 | 8.0% |
| Carver, MN | 5,438 | 46 | 8.0% |
| Independence, MN | 3,778 | 46 | 8.0% |
| Watertown, MN | 4,473 | 46 | 8.0% |
| City | Population | Air Quality Index | National Avg. |
| South Greeley, WY | 4,473 | 43 | 14.0% |
| Viroqua, WI | 4,472 | 35 | 30.0% |
| Westover, WV | 4,475 | 36 | 28.0% |
| Sherman, IL | 4,470 | 40 | 20.0% |
| Surfside Beach, SC | 4,470 | 14 | 72.0% |
| Watertown, MN | 4,473 | 46 | 8.0% |
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