| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 15°F | 36°F | 25°F | 3.2" |
| February | 15°F | 37°F | 26°F | 4.2" |
| March | 24°F | 44°F | 34°F | 4.0" |
| April | 34°F | 57°F | 45°F | 5.0" |
| May | 44°F | 67°F | 55°F | 4.5" |
| June | 53°F | 75°F | 63°F | 5.8" |
| July | 60°F | 82°F | 70°F | 4.3" |
| August | 58°F | 80°F | 69°F | 4.4" |
| September | 51°F | 74°F | 62°F | 4.1" |
| October | 41°F | 62°F | 51°F | 6.9" |
| November | 31°F | 52°F | 41°F | 4.4" |
| December | 21°F | 40°F | 30°F | 5.3" |
| Index | Portland | Maine | National |
| Air quality index | 40 | 33 | 42 |
| Pollution index | 2,043,700 | 3,417,521 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 308 |
| Days with moderate air quality | 56 |
| Days w/ poor A.Q. for sensitive groups | 1 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.030% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.003% |
| Lead | 0.030% |
| Mercury | 0.002% |
| City | Population | Air Quality Index | National Avg. |
| Little Falls, ME | 745 | 40 | 20.0% |
| Standish, ME | 198 | 40 | 20.0% |
| Cumberland Center, ME | 2,944 | 40 | 20.0% |
| Littlejohn Island, ME | 63 | 40 | 20.0% |
| Old Orchard Beach, ME | 8,952 | 40 | 20.0% |
| Portland, ME | 66,706 | 40 | 20.0% |
| City | Population | Air Quality Index | National Avg. |
| West Des Moines, IA | 66,724 | 39 | 22.0% |
| Redondo Beach, CA | 66,663 | 72 | 44.0% |
| Yuba City, CA | 66,660 | 44 | 12.0% |
| Oshkosh, WI | 66,753 | 36 | 28.0% |
| Kenner, LA | 66,759 | 45 | 10.0% |
| Portland, ME | 66,706 | 40 | 20.0% |
Here are the best places to live in Maine
Check out the 10 most dangerous cities in Maine
Check out the 10 safest cities in Maine
These are the 10 cheapest cities in Maine