| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 36°F | 46°F | 41°F | 3.8" |
| February | 37°F | 49°F | 42°F | 2.7" |
| March | 39°F | 52°F | 45°F | 4.4" |
| April | 42°F | 57°F | 48°F | 2.8" |
| May | 47°F | 64°F | 54°F | 2.2" |
| June | 51°F | 68°F | 58°F | 1.8" |
| July | 55°F | 74°F | 63°F | 0.7" |
| August | 56°F | 75°F | 63°F | 0.9" |
| September | 53°F | 69°F | 59°F | 2.0" |
| October | 47°F | 59°F | 52°F | 3.6" |
| November | 40°F | 51°F | 45°F | 5.7" |
| December | 35°F | 44°F | 39°F | 4.9" |
| Index | Machias | Washington | National |
| Air quality index | 45 | 36 | 42 |
| Pollution index | 15,778,900 | 4,541,850 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 236 |
| Days with moderate air quality | 127 |
| Days w/ poor A.Q. for sensitive groups | 2 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.010% |
| Benzene | 0.270% |
| Carbon Tetrachloride | 0.040% |
| Lead | 0.160% |
| Mercury | 0.003% |
| City | Population | Air Quality Index | National Avg. |
| Canyon Creek, WA | 3,311 | 24 | 52.0% |
| Arlington, WA | 20,435 | 24 | 52.0% |
| Verlot, WA | 582 | 24 | 52.0% |
| Lake Bosworth, WA | 1,110 | 24 | 52.0% |
| Lake Goodwin, WA | 4,743 | 24 | 52.0% |
| Machias, WA | 1,144 | 45 | 10.0% |
| City | Population | Air Quality Index | National Avg. |
| Hiawassee, GA | 1,144 | 37 | 26.0% |
| Dunlap, IL | 1,144 | 41 | 18.0% |
| West Brownsville, PA | 1,144 | 36 | 28.0% |
| Hotevilla-Bacavi, AZ | 1,145 | 45 | 10.0% |
| Sheridan, CA | 1,143 | 44 | 12.0% |
| Machias, WA | 1,144 | 45 | 10.0% |