| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 8°F | 31°F | 19°F | 5.0" |
| February | 10°F | 33°F | 21°F | 4.6" |
| March | 18°F | 41°F | 29°F | 4.3" |
| April | 30°F | 55°F | 42°F | 3.7" |
| May | 40°F | 66°F | 52°F | 4.3" |
| June | 49°F | 74°F | 61°F | 4.6" |
| July | 55°F | 81°F | 67°F | 4.7" |
| August | 53°F | 80°F | 65°F | 3.3" |
| September | 47°F | 73°F | 59°F | 3.8" |
| October | 36°F | 60°F | 48°F | 6.2" |
| November | 28°F | 48°F | 37°F | 5.8" |
| December | 16°F | 35°F | 25°F | 7.8" |
| Index | Calais | Maine | National |
| Air quality index | 31 | 33 | 42 |
| Pollution index | 3,235,100 | 3,417,521 | 2,726,193 |
| Measurement | Total |
| Days measured | 361 |
| Days with good air quality | 348 |
| Days with moderate air quality | 13 |
| 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 | 0.020% |
| Mercury | 0.010% |
| City | Population | Air Quality Index | National Avg. |
| Woodland, ME | 1,150 | 31 | 38.0% |
| Calais, ME | 3,129 | 31 | 38.0% |
| City | Population | Air Quality Index | National Avg. |
| Alva, FL | 3,129 | 36 | 28.0% |
| Fiskdale, MA | 3,128 | 40 | 20.0% |
| Huntingtown, MD | 3,130 | 47 | 6.0% |
| Benson, MN | 3,130 | 32 | 36.0% |
| Enderby, BC | 3,130 | n/a | |
| Calais, ME | 3,129 | 31 | 38.0% |