Climate and average weather in Portland
In Portland, the summers are mild, showery, and partly cloudy and the winters are very cold, snowy, and partly cloudy.
Over the course of the year, the temperature in Portland typically varies from 20°F to 71°F, and is rarely below 4°F or above 77°F. July is the hottest month of the year, while January is the coldest.
Based on the travel score, the best time of year to visit Portland for warm-weather activities is from mid June to late September.
- Hottest
- Jul
- 71°
- Coldest
- Jan
- 20°
- Wettest
- Oct
- 5.4 in
- Driest
- Jul
- 3.1 in
- Rain / yr
- 49.5 in
- 120 wet days
- Daylight
- 8.7–15.3 h
- shortest–longest
- Elevation
- 62 ft
- 43.7°N
- Clearest
- Sep
- 53% cloud
Portland is seat of Cumberland County, and largest city in State of Maine, United States.
- Density
- 372/km²
- people per km²
- Founded
- 1632
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Portland weather by month, at a glance
The whole year in one picture — sky, rain, humidity, temperature and travel score. Click any band to jump to its full chart.
Each stripe is one measure across the whole year, stacked so a single day reads top to bottom. The sky band runs overcast grey on top down to clear blue at the base — more blue means sunnier — followed by the rainfall curve, the humidity band, a temperature strip that tints each stretch of the year by how warm its average high is, and the travel-score line at the foot. Scan straight down any date to read that day across every measure at once; the score climbs highest around mid June to late September.
Temperature through the year
Daily average highs and lows in Portland, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.
The hot season lasts 3.8 months, from June 5 to September 28, with daily high temperatures above 62°F. The hottest month of the year in Portland is July, with an average high of 71°F and low of 63°F.
The cool season lasts 3.3 months, from December 9 to March 19, with daily high temperatures below 39°F. The coldest month of the year in Portland is January, with an average low of 20°F and high of 32°F.
Days typically run about 9°F warmer than nights year-round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 32 | 33 | 38 | 47 | 56 | 65 | 71 | 71 | 65 | 56 | 46 | 37 |
| Avg low (°F) | 20 | 21 | 28 | 38 | 47 | 56 | 63 | 63 | 57 | 47 | 37 | 28 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| Jan | 32 | 20 |
| Feb | 33 | 21 |
| Mar | 38 | 28 |
| Apr | 47 | 38 |
| May | 56 | 47 |
| Jun | 65 | 56 |
| Jul | 71 | 63 |
| Aug | 71 | 63 |
| Sep | 65 | 57 |
| Oct | 56 | 47 |
| Nov | 46 | 37 |
| Dec | 37 | 28 |
How hot and cold Portland really feels
The felt-temperature range through the year — heat index on the day's high (summer humidity), wind chill on the night's low (winter wind). The dashed lines are the plain thermometer; the gap is how much hotter or colder it really feels.
On the coldest nights, wind chill pulls the feels-like down to about 6°F (around January 23), with roughly 158 freezing days a year (feels-like at or below 32°F) — 69 of them bitterly cold — worst in January.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Feels-like high (°F) | 32 | 33 | 39 | 47 | 56 | 65 | 71 | 71 | 65 | 56 | 46 | 37 |
| Air high (°F) | 32 | 33 | 38 | 47 | 56 | 65 | 71 | 71 | 65 | 56 | 46 | 37 |
| Feels-like low (°F) | 8 | 9 | 18 | 31 | 43 | 56 | 63 | 63 | 57 | 43 | 30 | 17 |
| Air low (°F) | 20 | 21 | 28 | 38 | 47 | 56 | 63 | 63 | 57 | 47 | 37 | 28 |
| Feels-like high (°F) | Air high (°F) | Feels-like low (°F) | Air low (°F) | |
|---|---|---|---|---|
| Jan | 32 | 32 | 8 | 20 |
| Feb | 33 | 33 | 9 | 21 |
| Mar | 39 | 38 | 18 | 28 |
| Apr | 47 | 47 | 31 | 38 |
| May | 56 | 56 | 43 | 47 |
| Jun | 65 | 65 | 56 | 56 |
| Jul | 71 | 71 | 63 | 63 |
| Aug | 71 | 71 | 63 | 63 |
| Sep | 65 | 65 | 57 | 57 |
| Oct | 56 | 56 | 43 | 47 |
| Nov | 46 | 46 | 30 | 37 |
| Dec | 37 | 37 | 17 | 28 |
Average hourly temperature in Portland
A compact picture of the whole year, hour by hour: each column is a day, each row an hour, and the color is the modeled average temperature. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
Read left to right for the day of the year and top to bottom for the hour of the day; the color is the modeled temperature, cool blues through to hot reds on the same scale as the other charts. A vertical slice is a single day's swing — coolest just before dawn, warmest in the mid-afternoon — while a horizontal slice follows one hour across the seasons. The darker overlay marks night and the lighter one the twilight around sunrise and sunset. Colors run warmest on July afternoons, near 71°F, and coldest before dawn in January, near 20°F.
Portland weather by month
Every month at a glance. Click a month for its detailed page.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | 32° / 20° | 3.9 | 9.9 | 6.9 | 9.1 | 0.0 |
| Feb | 33° / 21° | 3.6 | 8.9 | 6.5 | 10.2 | 0.0 |
| Mar | 38° / 28° | 4.6 | 10.9 | 5.6 | 11.6 | 0.0 |
| Apr | 47° / 38° | 4.7 | 10.7 | 1.9 | 13.2 | 1.6 |
| May | 56° / 47° | 3.9 | 11 | 0.1 | 14.5 | 3.7 |
| Jun | 65° / 56° | 4.0 | 10.3 | 0 | 15.2 | 5.7 |
| Jul | 71° / 63° | 3.1 | 9.2 | 0 | 14.9 | 6.7 |
| Aug | 71° / 63° | 3.2 | 8.4 | 0 | 13.8 | 6.9 |
| Sep | 65° / 57° | 3.7 | 8.7 | 0 | 12.3 | 6.2 |
| Oct | 56° / 47° | 5.4 | 10.6 | 0.2 | 10.8 | 3.8 |
| Nov | 46° / 37° | 4.5 | 10.4 | 1.4 | 9.5 | 1.3 |
| Dec | 37° / 28° | 4.9 | 11 | 5.8 | 8.8 | 0.0 |
Chance of rain
How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.
Portland gets about 49.5 in of precipitation a year. On a typical day the chance of rain is often wet, but that rises and falls sharply with the seasons.
The wetter season lasts 4.1 months, from around Feb 21 to Jun 25, peaking in April at about 38% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Aug 27.
October is the wettest month by volume, with 5.4 in over about 11 wet days; July is the driest, with 3.1 in. Some of the cold-season precipitation falls as snow.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain on a day (%) | 32 | 32 | 35 | 36 | 35 | 33 | 30 | 27 | 29 | 34 | 35 | 35 |
| Rain days | 10 | 9 | 11 | 11 | 11 | 10 | 9 | 8 | 9 | 11 | 10 | 11 |
| Rain on a day (%) | Rain days | |
|---|---|---|
| Jan | 32 | 10 |
| Feb | 32 | 9 |
| Mar | 35 | 11 |
| Apr | 36 | 11 |
| May | 35 | 11 |
| Jun | 33 | 10 |
| Jul | 30 | 9 |
| Aug | 27 | 8 |
| Sep | 29 | 9 |
| Oct | 34 | 11 |
| Nov | 35 | 10 |
| Dec | 35 | 11 |
Monthly rainfall
Over a full year, Portland collects about 49.5 in of rain across 120 wet days — roughly 4.1 in in an average month.
It doesn’t fall evenly. October is the wettest month with 5.4 in, while July is the driest at just 3.1 in. The three wettest months alone bring about 30% of the year’s total, and some of the cold-season precipitation falls as snow.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rainfall (in) | 3.9 | 3.6 | 4.6 | 4.7 | 3.9 | 4.0 | 3.1 | 3.2 | 3.7 | 5.4 | 4.5 | 4.9 |
| Rain days | 10 | 9 | 11 | 11 | 11 | 10 | 9 | 8 | 9 | 11 | 10 | 11 |
| Snow days | 7 | 7 | 6 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 6 |
| Rainfall (in) | Rain days | Snow days | |
|---|---|---|---|
| Jan | 3.9 | 10 | 7 |
| Feb | 3.6 | 9 | 7 |
| Mar | 4.6 | 11 | 6 |
| Apr | 4.7 | 11 | 2 |
| May | 3.9 | 11 | 0 |
| Jun | 4.0 | 10 | 0 |
| Jul | 3.1 | 9 | 0 |
| Aug | 3.2 | 8 | 0 |
| Sep | 3.7 | 9 | 0 |
| Oct | 5.4 | 11 | 0 |
| Nov | 4.5 | 10 | 1 |
| Dec | 4.9 | 11 | 6 |
Snow in Portland
Average snowy days through the year, the snow-season span, and estimated snowfall — for ski trips and the perennial 'will there be snow at Christmas?' question.
Portland averages about 28 snowy days a year. Snow season runs roughly Nov 1 to Apr 27 — about 5.9 months.
February is snowiest, with roughly 7 days of snow and an estimated 20 in of snowfall. Over the year that adds up to an estimated 80 in of snow.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Snow days | 7 | 7 | 6 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 6 |
| Snowfall (in) | 18 | 20 | 18 | 5 | 0 | 0 | 0 | 0 | 0 | 0 | 4 | 15 |
| Snow days | Snowfall (in) | |
|---|---|---|
| Jan | 7 | 18 |
| Feb | 7 | 20 |
| Mar | 6 | 18 |
| Apr | 2 | 5 |
| May | 0 | 0 |
| Jun | 0 | 0 |
| Jul | 0 | 0 |
| Aug | 0 | 0 |
| Sep | 0 | 0 |
| Oct | 0 | 0 |
| Nov | 1 | 4 |
| Dec | 6 | 15 |
Clouds and sunshine
How often the daytime sky is clear, partly cloudy or overcast.
In Portland, the average share of the sky covered by clouds shows moderate seasonal variation over the course of the year.
The clearer part of the year begins around June 27 and lasts for 5.1 months, ending around November 27. The clearest month is August, when the sky is clear, mostly clear, or partly cloudy 56% of the time on average.
The cloudier part of the year begins around February 20 and lasts for 4.2 months, ending around June 26. The cloudiest month is May, when it is overcast or mostly cloudy 60% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 50 | 49 | 44 | 41 | 40 | 44 | 52 | 56 | 55 | 52 | 49 | 45 |
| Cloudier (%) | 50 | 51 | 56 | 59 | 60 | 56 | 48 | 44 | 45 | 48 | 51 | 55 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| Jan | 50 | 50 |
| Feb | 49 | 51 |
| Mar | 44 | 56 |
| Apr | 41 | 59 |
| May | 40 | 60 |
| Jun | 44 | 56 |
| Jul | 52 | 48 |
| Aug | 56 | 44 |
| Sep | 55 | 45 |
| Oct | 52 | 48 |
| Nov | 49 | 51 |
| Dec | 45 | 55 |
Daylight, sunrise and sunset
Hours of daylight through the year, with sunrise and sunset times.
The gold band is daylight — sunrise runs along its lower edge, sunset along the upper — so it widens toward summer and pinches toward winter, with night the dark area above and below. The longest day, around June 19, brings about 15 h 18 min of light; the shortest, around December 19, only 8 h 42 min — a swing of roughly 6 h 36 min.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 9.1 | 10.2 | 11.6 | 13.2 | 14.5 | 15.2 | 14.9 | 13.8 | 12.3 | 10.8 | 9.5 | 8.8 |
| Sunrise (AM) | 7:18 | 6:49 | 6:02 | 5:05 | 4:22 | 4:04 | 4:18 | 4:51 | 5:27 | 6:03 | 6:43 | 7:14 |
| Sunset (PM) | 4:23 | 5:02 | 5:40 | 6:17 | 6:53 | 7:18 | 7:15 | 6:40 | 5:44 | 4:49 | 4:09 | 4:00 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| Jan | 9.1 | 7:18 | 4:23 |
| Feb | 10.2 | 6:49 | 5:02 |
| Mar | 11.6 | 6:02 | 5:40 |
| Apr | 13.2 | 5:05 | 6:17 |
| May | 14.5 | 4:22 | 6:53 |
| Jun | 15.2 | 4:04 | 7:18 |
| Jul | 14.9 | 4:18 | 7:15 |
| Aug | 13.8 | 4:51 | 6:40 |
| Sep | 12.3 | 5:27 | 5:44 |
| Oct | 10.8 | 6:03 | 4:49 |
| Nov | 9.5 | 6:43 | 4:09 |
| Dec | 8.8 | 7:14 | 4:00 |
Sunny days
How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.
Portland averages about 10 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 7 and 13 days.
The sunnier stretch runs 4.3 months, from around Aug 8 to Dec 15. The sunniest month is August, with roughly 11 sunny days (mixed).
The greyest month is May, down near 8 sunny days — about 32% fewer than the August peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sunny days | 11 | 9 | 9 | 8 | 8 | 8 | 9 | 11 | 12 | 11 | 10 | 10 |
| Sky | Mixed | Mixed | Mixed | Gloomy | Gloomy | Gloomy | Mixed | Mixed | Mixed | Mixed | Mixed | Mixed |
| Sunny days | Sky | |
|---|---|---|
| Jan | 11 | Mixed |
| Feb | 9 | Mixed |
| Mar | 9 | Mixed |
| Apr | 8 | Gloomy |
| May | 8 | Gloomy |
| Jun | 8 | Gloomy |
| Jul | 9 | Mixed |
| Aug | 11 | Mixed |
| Sep | 12 | Mixed |
| Oct | 11 | Mixed |
| Nov | 10 | Mixed |
| Dec | 10 | Mixed |
Humidity comfort
Share of days at each humidity comfort level, based on the dew point — the measure that tracks how muggy it actually feels.
Humidity comfort is graded by the dew point — the temperature at which the air would be fully saturated — because it tracks how muggy it actually feels far better than relative humidity does. A low dew point feels dry and crisp; a high one feels sticky and oppressive no matter the reading on a humidity gauge.
In Portland, how humid it feels changes dramatically over the year.
The more humid part of the year lasts 3.3 months, from around June 16 to September 23. The muggiest month is July, when the air feels humid, muggy or worse about 55% of the time.
The most comfortable stretch runs from around September 24 to June 15, and May is the most comfortable month — the air is dry or comfortable 100% of the time.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 100 | 100 | 100 | 100 | 96 | 57 | 11 | 13 | 51 | 92 | 100 | 100 |
| Comfortable (%) | 0 | 0 | 0 | 0 | 4 | 28 | 34 | 32 | 29 | 7 | 0 | 0 |
| Humid (%) | 0 | 0 | 0 | 0 | 0 | 14 | 40 | 40 | 17 | 1 | 0 | 0 |
| Muggy (%) | 0 | 0 | 0 | 0 | 0 | 1 | 15 | 15 | 3 | 0 | 0 | 0 |
| Dry (%) | Comfortable (%) | Humid (%) | Muggy (%) | |
|---|---|---|---|---|
| Jan | 100 | 0 | 0 | 0 |
| Feb | 100 | 0 | 0 | 0 |
| Mar | 100 | 0 | 0 | 0 |
| Apr | 100 | 0 | 0 | 0 |
| May | 96 | 4 | 0 | 0 |
| Jun | 57 | 28 | 14 | 1 |
| Jul | 11 | 34 | 40 | 15 |
| Aug | 13 | 32 | 40 | 15 |
| Sep | 51 | 29 | 17 | 3 |
| Oct | 92 | 7 | 1 | 0 |
| Nov | 100 | 0 | 0 | 0 |
| Dec | 100 | 0 | 0 | 0 |
Wind
Average wind speed through the year, banded into plain-language speed zones so a number reads as 'breezy' or 'calm' without knowing the scale.
This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.
Across the year, average wind speed in Portland is typically light breeze, near 10 mph, and varies moderately with the seasons.
The windier part of the year lasts 6.3 months, from around Oct 9 to Apr 17. The windiest month is January, averaging about 12 mph (light breeze).
The calmer part of the year runs from around Apr 18 to Oct 8, with August the calmest month at about 8 mph.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (mph) | 12 | 11 | 11 | 10 | 9 | 8 | 8 | 8 | 9 | 10 | 11 | 11 |
| Feels | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze | light breeze |
| Wind speed (mph) | Feels | |
|---|---|---|
| Jan | 12 | light breeze |
| Feb | 11 | light breeze |
| Mar | 11 | light breeze |
| Apr | 10 | light breeze |
| May | 9 | light breeze |
| Jun | 8 | light breeze |
| Jul | 8 | light breeze |
| Aug | 8 | light breeze |
| Sep | 9 | light breeze |
| Oct | 10 | light breeze |
| Nov | 11 | light breeze |
| Dec | 11 | light breeze |
Hazard calendar for Portland
When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.
Portland sits in the Atlantic hurricane belt; the season peaks August–October.
Best time to visit Portland
To characterize how pleasant the weather is in Portland throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.
Around late June, Portland is still near the start of its best-weather window — great conditions with the peak-season crowds not yet at full swing.
Inferred from the travel-score curve; month-by-month visitor numbers are a planned addition.
The travel score favors clear, rainless days with daytime highs between 64°F and 82°F. Based on this score, the best time of year to visit Portland for general outdoor tourist activities is from mid June to late September, with a peak score in the last week of August.
The travel score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Travel score (0–10) | 0.0 | 0.0 | 0.1 | 1.6 | 3.7 | 5.7 | 6.7 | 6.9 | 6.1 | 3.8 | 1.3 | 0.0 |
| Rating | poor | poor | poor | poor | fair | good | good | good | good | fair | poor | poor |
| Travel score (0–10) | Rating | |
|---|---|---|
| Jan | 0.0 | poor |
| Feb | 0.0 | poor |
| Mar | 0.1 | poor |
| Apr | 1.6 | poor |
| May | 3.7 | fair |
| Jun | 5.7 | good |
| Jul | 6.7 | good |
| Aug | 6.9 | good |
| Sep | 6.1 | good |
| Oct | 3.8 | fair |
| Nov | 1.3 | poor |
| Dec | 0.0 | poor |
The beach/pool score favors clear, rainless days with daytime highs between 75°F and 93°F. Based on this score, the best time of year to visit Portland for hot-weather activities is from early July to late August, with a peak score in the first week of August.
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).
What to pack for Portland, by month
Month by month, what's worth putting in the bag — from the temperature range, rain chance, sun and wind. Tap a month for a quick packing note.
For a warm-season trip around July (highs near 71°F), the essentials are rain gear and sun protection. In the cold season around January (highs near 32°F), pack a warm layer, a heavy coat and rain gear.
In July, Portland sees daytime highs around 71°F and nights near 63°F. Pack sun protection. Worth having: rain gear. About 9 days see rain.
Sea temperature near Portland
Average ocean temperature at the nearest coast, month by month, banded into swim-comfort zones — the other half of the beach question.
The sea offshore is warmest in August at about 63°F and coldest in March near 38°F.
The water stays below 68°F all year — cool enough that most swimmers want a wetsuit.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°F) | 42 | 39 | 38 | 42 | 48 | 55 | 62 | 63 | 60 | 54 | 49 | 45 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Cool | Cool | Cool | Bracing | Bracing | Bracing |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 42 | Bracing |
| Feb | 39 | Bracing |
| Mar | 38 | Bracing |
| Apr | 42 | Bracing |
| May | 48 | Bracing |
| Jun | 55 | Bracing |
| Jul | 62 | Cool |
| Aug | 63 | Cool |
| Sep | 60 | Cool |
| Oct | 54 | Bracing |
| Nov | 49 | Bracing |
| Dec | 45 | Bracing |
UV index (midday) in Portland by month
Clear-sky midday UV index through the year, shaded by the WHO exposure levels — how much sun protection each month calls for.
Under clear skies, the midday UV index in Portland peaks around July 12 at about 7 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 23 at about 1 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 7 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 1 | 2 | 4 | 5 | 7 | 7 | 7 | 4 | 6 | 3 | 2 | 1 |
| Level | Low | Moderate | Moderate | Moderate | High | High | Very high | Moderate | High | Moderate | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 1 | Low |
| Feb | 2 | Moderate |
| Mar | 4 | Moderate |
| Apr | 5 | Moderate |
| May | 7 | High |
| Jun | 7 | High |
| Jul | 7 | Very high |
| Aug | 4 | Moderate |
| Sep | 6 | High |
| Oct | 3 | Moderate |
| Nov | 2 | Low |
| Dec | 1 | Low |
Average hourly UV index in Portland
Modeled clear-sky UV for every hour of every day — when in the day sun protection actually matters.
The whole year hour by hour: each column is a day, each row an hour, and the color is the modeled clear-sky UV index — the midday peak scaled down as the sun sits lower in the sky. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.
UV falls off far faster than brightness as the sun drops, so even in July the burn window is concentrated in the middle of the day: about 7.5 hours a day reach index 3 (protection recommended), and 3.5 hours reach 6 or more. Mornings and late afternoons stay comparatively gentle year round.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV ≥ 3 (h/day) | 0 | 0 | 3.5 | 5.5 | 7 | 7.5 | 7.5 | 5 | 5.5 | 0 | 0 | 0 |
| UV ≥ 6 (h/day) | 0 | 0 | 0 | 0 | 2.5 | 2.5 | 3.5 | 0 | 0 | 0 | 0 | 0 |
| UV ≥ 3 (h/day) | UV ≥ 6 (h/day) | |
|---|---|---|
| Jan | 0 | 0 |
| Feb | 0 | 0 |
| Mar | 3.5 | 0 |
| Apr | 5.5 | 0 |
| May | 7 | 2.5 |
| Jun | 7.5 | 2.5 |
| Jul | 7.5 | 3.5 |
| Aug | 5 | 0 |
| Sep | 5.5 | 0 |
| Oct | 0 | 0 |
| Nov | 0 | 0 |
| Dec | 0 | 0 |
Growing season
The growing season in Portland typically lasts about 250 days, from around March 28 to December 2 — the span where a frost-free day is more likely than not. It is reliably frost-free from April 15 to November 7.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Frost-free chance (%) | 14 | 14 | 33 | 88 | 100 | 100 | 100 | 100 | 100 | 99 | 78 | 32 |
| Frost nights | 31 | 28 | 31 | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 23 | 31 |
| Frost-free chance (%) | Frost nights | |
|---|---|---|
| Jan | 14 | 31 |
| Feb | 14 | 28 |
| Mar | 33 | 31 |
| Apr | 88 | 13 |
| May | 100 | 0 |
| Jun | 100 | 0 |
| Jul | 100 | 0 |
| Aug | 100 | 0 |
| Sep | 100 | 0 |
| Oct | 99 | 0 |
| Nov | 78 | 23 |
| Dec | 32 | 31 |
Growing degree days
Growing degree days tally heat above 50°F: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. Portland banks about 1,830 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around July.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Growing degree days (°F·days) | 0 | 0 | 0 | 0 | 63 | 321 | 527 | 522 | 330 | 66 | 0 | 0 |
| Growing degree days (°F·days) | |
|---|---|
| Jan | 0 |
| Feb | 0 |
| Mar | 0 |
| Apr | 0 |
| May | 63 |
| Jun | 321 |
| Jul | 527 |
| Aug | 522 |
| Sep | 330 |
| Oct | 66 |
| Nov | 0 |
| Dec | 0 |
Solar energy
Average daily shortwave solar energy reaching the ground, banded into brightness zones so the number means something at a glance.
Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.
Portland receives about 3.9 kWh/m² a day of solar energy on average — moderate — with a clear seasonal swing between 1.5 and 6.1 kWh/m².
The brighter stretch of the year lasts 6.3 months, from around Mar 15 to Sep 22. The brightest month is July, averaging about 6.0 kWh/m² (bright).
The dimmest month is December, down near 1.5 kWh/m² — roughly 75% less than the July peak.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 1.8 | 2.8 | 3.9 | 4.9 | 5.5 | 5.9 | 6.0 | 5.4 | 4.2 | 2.8 | 1.9 | 1.5 |
| Level | Dim | Moderate | Moderate | Bright | Bright | Bright | Intense | Bright | Bright | Moderate | Dim | Dim |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| Jan | 1.8 | Dim |
| Feb | 2.8 | Moderate |
| Mar | 3.9 | Moderate |
| Apr | 4.9 | Bright |
| May | 5.5 | Bright |
| Jun | 5.9 | Bright |
| Jul | 6.0 | Intense |
| Aug | 5.4 | Bright |
| Sep | 4.2 | Bright |
| Oct | 2.8 | Moderate |
| Nov | 1.9 | Dim |
| Dec | 1.5 | Dim |
Where is Portland?
Portland sits at 43.7°N, 70.3°W, 62 ft above sea level, in United States. The nearest listed city is South Portland, 1.2 mi away.
What Portland looks like
Topography around Portland
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Portland.
Within 2 miles, the terrain around Portland has only modest variations in elevation — a maximum elevation change of 180 ft around an average of 30 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 548 ft; within 50 miles, large variations in elevation — a maximum elevation change of 2,352 ft.
The land around Portland is covered by water (40%), artificial surfaces (31%) and trees (21%) within 2 miles, trees (43%) and water (39%) within 10 miles, and trees (61%) and water (33%) within 50 miles.
United States travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 100% of US
- price level, 2025
- GDP per capita
- $90,027
- 2025
- Happiness
- 6.8 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 5.8
- per 100k, 2023
- Road deaths
- 12.7
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Portland (43.6574°, -70.2589°, elevation 62 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).