Photo: PhilipC · CC BY 2.0Portland has cooler summers than 95% of U.S. towns
January mornings start at about 16°. Temperatures cover 63° across the year, low to high. Winter nights are cold: in January they are colder than in 82% of U.S. towns. Warm coats and heating bills mark the months from November to April, when means dip under 50°.
A year in Portland at a glance
Each month’s typical high and low, and what it brings.
What stands out about Portland’s climate
Compared with towns across the U.S., with Portland’s place in Maine beside it.
What a year in Portland feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 170 frost-free days a year
In half of years the last 32° night comes by April 26 and the first by October 15. Frost and day counts come from NOAA’s station at Portland International Jetport, ME, 6 miles from the city’s center point, at about the same height.
The 2023 USDA map puts Portland’s center in zone 6a: the coldest night of a typical winter, averaged over 1991–2020, reaches about −6°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 69 inches of snow a winter
Snow, measured at Portland International Jetport, ME, falls mostly in January. Precipitation (rain plus melted snow) adds up to 49 inches a year; October is the wettest month and January the driest. Rain or snow falls on about 131 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Portland
94% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through May.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Portland International Jetport, ME.
Living with Portland’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
170 frost-free days in zone 6a. The last frost comes by Apr 26 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 15.
Months with highs of 62–84° and lows of 40° or more: May, June, July, August and September. 69 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Portland from natural hazards, river flooding is the largest share (33%); heat waves, cold waves, winter storms and ice storms together are 22%. Normals are averages; the hazards page covers the extremes.
Natural hazards →Portland and its neighbors
Westbrook has the coldest January nights next door (14°, 2° colder) and Westbrook the hottest July afternoons (80°, 1° warmer). Differences under a degree are within what the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Portland’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Portland, ME | 16° | 79° | 49" | 69" |
| Walton, NY | 13° | 80° | 47" | 71" |
| Dalton, MA | 13° | 80° | 48" | 77" |
| Bradford, PA | 15° | 80° | 44" | 75" |
| Litchfield, CT | 15° | 81° | 51" | 59" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Portland averaged 1.9° warmer than the 1900s. The biggest change is in December (+3.6°).
A bigger shift than in 85% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Portland compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Portland’s place among Maine’s.
Portland weather by month
Highs, lows and precipitation from NOAA’s grid at Portland’s center; snow, wet days and snow on the ground from Portland International Jetport, ME. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 32° | 16° | 3.4" | 18.6" | 11 | 23 | 14° – 31° |
| February | 35° | 17° | 3.5" | 16.6" | 10 | 21 | 14° – 32° |
| March | 42° | 26° | 4.2" | 13.6" | 11 | 16 | 27° – 41° |
| April | 53° | 35° | 4.4" | 2.8" | 11 | 2 | 41° – 49° |
| May | 63° | 45° | 3.8" | 0.0" | 13 | 0 | 49° – 59° |
| June | 73° | 55° | 4.4" | 0.0" | 12 | 0 | 61° – 67° |
| July | 79° | 61° | 3.5" | 0.0" | 11 | 0 | 65° – 73° |
| August | 78° | 60° | 3.5" | 0.0" | 9 | 0 | 66° – 72° |
| September | 70° | 52° | 3.9" | 0.0" | 9 | 0 | 57° – 66° |
| October | 58° | 42° | 5.0" | 0.2" | 11 | 0 | 46° – 57° |
| November | 48° | 32° | 4.4" | 2.3" | 11 | 2 | 35° – 44° |
| December | 38° | 23° | 4.6" | 14.6" | 12 | 11 | 24° – 38° |
| Year | 56° | 38° | 48.5" | 68.7" | 131 | 74 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 14° to 32°. August is the most reliable, staying within 6°.
Where Portland’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Portland’s center.
- Snow: Portland International Jetport, ME.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Portland International Jetport, ME, 6 miles from the city’s center point, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Portland’s climate
What is the weather like in Portland?
A typical July afternoon reaches 79°, a January night drops to 16°, and about 69 inches of snow falls in a normal winter. Colder January nights than 82% of U.S. towns; cooler July afternoons than 95% of U.S. towns.
How cold does it get in Portland in winter?
January nights average 16°. About 144 nights a year reach 32° or below and 7 reach 0° or below. In the coldest January of the last 30 years the month averaged 14°.
How much snow does Portland get?
About 69 inches in a normal winter at Portland International Jetport, ME, most of it in January, with snow on the ground about 74 days a year.
How hot does it get in Portland?
July, with a typical high of 79° and a low of 61°. About 5 days a year reach 90° (Portland International Jetport, ME).
When is the first and last frost in Portland?
In half of years the last spring frost (32°) comes by April 26 and the first fall frost by October 15, about 170 frost-free days, at Portland International Jetport, ME.
What growing zone is Portland in?
Zone 6a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −6°.
What is the best time of year to visit Portland?
By one simple rule (highs of 62–84° and lows of 40° or more), May, June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Portland getting warmer?
Yes: 1991–2020 averaged 1.9° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 85% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Portland.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.