Weather and climate in Portland, ME
What the weather is like in Portland
The warmest month in Portland is August, with average highs of 70°F. The coolest is January, when nights average 25°F. About 53.6 in of rain and snow falls in a typical year, most in October and least in August.
Skies are clearest in September (49% average cloud cover) and cloudiest in January (73%). Combining cloud with the length of truly dark nights, September, October, November offer the most clear, dark hours for stargazing.
Clear, dark hours per night
Hours of full astronomical darkness in mid-month, multiplied by the average share of clear sky. A rough guide to how much good observing time a typical night offers.
Monthly averages
| Month | High | Low | Precipitation | Cloud cover | Humidity | Wind | Dark hours |
|---|---|---|---|---|---|---|---|
| January | 34°F | 25°F | 4.1 in | 73% | 85% | 11 mph | 11.3 h |
| February | 35°F | 26°F | 4.0 in | 68% | 83% | 11 mph | 10.2 h |
| March | 39°F | 31°F | 4.3 in | 64% | 81% | 10 mph | 8.9 h |
| April | 46°F | 38°F | 4.8 in | 62% | 83% | 8 mph | 7.0 h |
| May | 54°F | 47°F | 4.0 in | 66% | 87% | 6 mph | 5.1 h |
| June | 62°F | 56°F | 5.0 in | 63% | 88% | 6 mph | 3.8 h |
| July | 69°F | 63°F | 3.8 in | 55% | 88% | 5 mph | 4.5 h |
| August | 70°F | 63°F | 3.7 in | 50% | 86% | 6 mph | 6.4 h |
| September | 65°F | 58°F | 3.8 in | 49% | 83% | 7 mph | 8.2 h |
| October | 56°F | 49°F | 5.7 in | 60% | 81% | 9 mph | 9.8 h |
| November | 47°F | 40°F | 4.9 in | 67% | 81% | 10 mph | 11.0 h |
| December | 40°F | 31°F | 5.6 in | 72% | 83% | 11 mph | 11.6 h |
Climate averages: NASA POWER, 2001–2025, for the grid area around 43.50, -70.00 (about 50 km across). High and low temperatures are estimated from the monthly mean and the average daily range. Hills, coasts and cities can differ from the area average. Aurora outlook for Portland · Sources and methods.