| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 20°F | 33°F | 27°F | 1.2" |
| February | 22°F | 34°F | 28°F | 1.3" |
| March | 30°F | 48°F | 38°F | 5.9" |
| April | 38°F | 58°F | 47°F | 5.4" |
| May | 52°F | 72°F | 61°F | 4.9" |
| June | 59°F | 80°F | 69°F | 6.0" |
| July | 65°F | 87°F | 76°F | 6.0" |
| August | 61°F | 82°F | 71°F | 7.8" |
| September | 52°F | 72°F | 61°F | 6.1" |
| October | 42°F | 63°F | 51°F | 3.5" |
| November | 33°F | 50°F | 41°F | 4.7" |
| December | 26°F | 36°F | 31°F | 2.5" |
| Index | Portland | Michigan | National |
| Air quality index | 36 | 69 | 42 |
| Pollution index | 1,401,450 | 4,161,606 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 330 |
| Days with moderate air quality | 35 |
| Days w/ poor A.Q. for sensitive groups | 0 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.020% |
| Carbon Tetrachloride | 0.002% |
| Lead | 0.005% |
| Mercury | 0.000% |
| City | Population | Air Quality Index | National Avg. |
| Eagle, MI | 116 | 36 | 28.0% |
| Sunfield, MI | 676 | 36 | 28.0% |
| Westphalia, MI | 808 | 36 | 28.0% |
| Grand Ledge, MI | 7,860 | 36 | 28.0% |
| Wacousta, MI | 1,698 | 36 | 28.0% |
| Portland, MI | 3,931 | 36 | 28.0% |
| City | Population | Air Quality Index | National Avg. |
| Rumford, ME | 3,931 | 40 | 20.0% |
| Oracle, AZ | 3,932 | 47 | 6.0% |
| Skippack, PA | 3,928 | 51 | 2.0% |
| Potosi, TX | 3,928 | 33 | 34.0% |
| Presidio, TX | 3,928 | 47 | 6.0% |
| Portland, MI | 3,931 | 36 | 28.0% |
Here are the best places to live in Michigan
Safest States In The US
See the best places to live in Portland
Check out the 10 most dangerous cities in Michigan