| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 11°F | 31°F | 20°F | 3.2" |
| February | 10°F | 32°F | 20°F | 3.6" |
| March | 20°F | 42°F | 30°F | 5.4" |
| April | 33°F | 55°F | 43°F | 14.7" |
| May | 42°F | 64°F | 52°F | 8.7" |
| June | 53°F | 78°F | 64°F | 6.1" |
| July | 57°F | 81°F | 68°F | 4.3" |
| August | 57°F | 82°F | 68°F | 6.4" |
| September | 50°F | 75°F | 61°F | 5.1" |
| October | 43°F | 61°F | 51°F | 8.4" |
| November | 29°F | 47°F | 37°F | 8.4" |
| December | 15°F | 35°F | 24°F | 5.6" |
| Index | Gray | 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% |
| Lewiston, ME | 36,158 | 31 | 38.0% |
| Lisbon Falls, ME | 4,079 | 31 | 38.0% |
| Casco, ME | 717 | 31 | 38.0% |
| Auburn, ME | 23,267 | 31 | 38.0% |
| Gray, ME | 747 | 31 | 38.0% |
| City | Population | Air Quality Index | National Avg. |
| Town of Pines, IN | 747 | 37 | 26.0% |
| Karlstad, MN | 747 | 33 | 34.0% |
| Twin Valley, MN | 747 | 33 | 34.0% |
| Meadville, MS | 747 | 44 | 12.0% |
| Interlaken, NJ | 747 | 51 | 2.0% |
| Gray, ME | 747 | 31 | 38.0% |
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