| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 13°F | 31°F | 21°F | 4.0" |
| February | 14°F | 32°F | 22°F | 3.8" |
| March | 22°F | 41°F | 31°F | 5.3" |
| April | 35°F | 55°F | 44°F | 6.6" |
| May | 45°F | 67°F | 55°F | 4.4" |
| June | 54°F | 73°F | 62°F | 6.1" |
| July | 60°F | 79°F | 69°F | 5.8" |
| August | 57°F | 78°F | 67°F | 6.7" |
| September | 51°F | 71°F | 60°F | 6.9" |
| October | 41°F | 59°F | 50°F | 7.4" |
| November | 30°F | 47°F | 38°F | 6.8" |
| December | 19°F | 35°F | 26°F | 4.1" |
| Index | Waterville | Maine | National |
| Air quality index | 28 | 33 | 42 |
| Pollution index | 3,644,290 | 3,417,521 | 2,726,193 |
| Measurement | Total |
| Days measured | 361 |
| Days with good air quality | 356 |
| Days with moderate air quality | 5 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.030% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.030% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Winslow, ME | 4,908 | 28 | 44.0% |
| Clinton, ME | 1,227 | 28 | 44.0% |
| Fairfield, ME | 2,298 | 28 | 44.0% |
| Oakland, ME | 2,324 | 28 | 44.0% |
| Norridgewock, ME | 1,272 | 28 | 44.0% |
| Waterville, ME | 16,623 | 28 | 44.0% |
| City | Population | Air Quality Index | National Avg. |
| Camp Pendleton South, CA | 16,618 | 64 | 28.0% |
| Ham Lake, MN | 16,630 | 46 | 8.0% |
| Dallas, OR | 16,612 | 32 | 36.0% |
| McKinleyville, CA | 16,645 | 27 | 46.0% |
| Madison, NJ | 16,647 | 51 | 2.0% |
| Waterville, ME | 16,623 | 28 | 44.0% |
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