| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 12°F | 32°F | 22°F | 4.9" |
| February | 14°F | 33°F | 23°F | 5.4" |
| March | 22°F | 42°F | 32°F | 6.5" |
| April | 34°F | 55°F | 44°F | 6.8" |
| May | 44°F | 66°F | 55°F | 5.8" |
| June | 53°F | 73°F | 63°F | 9.6" |
| July | 59°F | 80°F | 69°F | 8.9" |
| August | 56°F | 79°F | 67°F | 6.4" |
| September | 49°F | 72°F | 60°F | 7.0" |
| October | 39°F | 60°F | 49°F | 9.0" |
| November | 29°F | 48°F | 38°F | 7.0" |
| December | 19°F | 36°F | 27°F | 5.4" |
| Index | Casco | Maine | National |
| Air quality index | 31 | 33 | 42 |
| Pollution index | 2,712,920 | 3,417,521 | 2,726,193 |
| Measurement | Total |
| Days measured | 361 |
| Days with good air quality | 345 |
| Days with moderate air quality | 16 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.010% |
| Lead | 0.050% |
| Mercury | 0.070% |
| City | Population | Air Quality Index | National Avg. |
| Naples, ME | 555 | 31 | 38.0% |
| Auburn, ME | 23,267 | 31 | 38.0% |
| Bridgton, ME | 1,850 | 31 | 38.0% |
| Oxford, ME | 1,026 | 31 | 38.0% |
| Gray, ME | 747 | 31 | 38.0% |
| Casco, ME | 717 | 31 | 38.0% |
| City | Population | Air Quality Index | National Avg. |
| Elaine, AR | 717 | 43 | 14.0% |
| Dennehotso, AZ | 717 | 49 | 2.0% |
| Dalton City, IL | 717 | 44 | 12.0% |
| Crab Orchard, KY | 717 | 33 | 34.0% |
| Napi Headquarters, NM | 717 | 49 | 2.0% |
| Casco, ME | 717 | 31 | 38.0% |
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