Portland, OR Climate: Temperature & Rain by Month
Pulled from NOAA NCEI 1991–2020 normals →: climate measurements used in PlainClimate's documented score
30-year climate normals (1991-2020) from Portland's primary NOAA station, PORTLAND INTL AP - 2 stations mapped to the area.
The climate verdict for Portland
A compact 29°F seasonal swing gives Portland, Oregon a steadier-than-extreme annual shape. NOAA reports an annual average of 55°F. It scores 87/100 for climate comfort (excellent), putting it in the top third of station-mapped location scores and exceeding 87% of them.
- 55°F
- annual average temperature (NOAA normal)
- 87/100
- comfort score, above 87% of station-mapped location scores
- 36.9"
- annual precipitation · 4" snow
- 251 days
- growing season, frost-free days
Portland: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USW00024229 · Portland, OR 55°F mean · 36.9" precip
TEMP-MILD · RANK-UPPER · PHOTO-FINISH · PRCP-MID · SWING-NARROW · COMF-TOP · LOAD-HEAT · STN-MULTI · BOOK-FULL
- TEMP-MILD 55°F
- RANK-UPPER #4,185
- PHOTO-FINISH ≈ Lebanon
- PRCP-MID 36.9"
- SWING-NARROW 29°F
- COMF-TOP 87/100
- LOAD-HEAT 4,104 HDD
- STN-MULTI USW00024229
- BOOK-FULL 6/6 fields
Nearest mean-temperature peer: Lebanon, OR ( -0.2 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every OR station list.
- Portland (this station) 55°F
- Cold Portland Kgw-tv, OR 55°F
- Near Lebanon, OR 55°F
- Near Winchester, OR 55°F
- Near Aurora State, OR 55°F
Climate Living Index · Portland
Portland: 84/100 · grade B
Portland publishes all six Living Index dimensions from NOAA annual/seasonal normals · NOAA daily multivariate normals · NOAA hourly normals.
PlainClimate-derived for Portland, not an official NOAA rating. Rankings still use Comfort Score 87/100 (separate formula). Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Normal heat + freeze calendar | 0 calendar days | 100/100 · A |
| Summer moisture balance | 53.4°F mean dew point | 95/100 · A |
| Precipitation balance | 36.9 in · 1.9 from 35 in | 92/100 · A |
| Frost-free season | 251 days/year | 89/100 · A |
| Snowfall burden | 4.2 inches/year | 72/100 · B |
| Annual temperature balance | 55.1°F · 12.4° from 67.5°F | 60/100 · C |
Portland · 2026-08-04 · NOAA NCEI Climate Normals · method · Comfort Score method.
Portland is a temperate Köppen climate: Csb
Coldest-month mean 41.6°F and warmest-month mean 70.6°F place this station in temperate, dry-summer, warm summer climates (Csb). Class Csb is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: temperate, specifically temperate, dry-summer, warm summer.
- Köppen code
- Csb
- Group
- Temperate
- Warmest month
- 70.6°F
- Coldest month
- 41.6°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · heating-led station
Where Portland sits across the climate record
Three NOAA fields for Portland's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- 61st percentile warmth
- Mid-pack annual mean versus 6,861 station normals.
- Annual precipitation
- 51st percentile wetness
- Neither arid nor torrential versus 6,352 station totals.
- Seasonal temperature swing
- Narrower than 92%
- Warmest-to-coldest month gap for Portland is compact versus 6,861 complete station-years.
How Portland compares across U.S. station-mapped locations
Portland's comfort score vs. all station-mapped locations
PlainClimate composite comfort index (1–100), NOAA 1991–2020 normals
87 Top 13% score exceeds 87% of 6,189 station-mapped location scores
- 0–10: 0 station-mapped locations (0%). Below this entry.
- 10–20: 0 station-mapped locations (0%). Below this entry.
- 20–30: 96 station-mapped locations (2%). Below this entry.
- 30–40: 280 station-mapped locations (5%). Below this entry.
- 40–50: 1,113 station-mapped locations (18%). Below this entry.
- 50–60: 1,329 station-mapped locations (21%). Below this entry.
- 60–70: 1,236 station-mapped locations (20%). Below this entry.
- 70–80: 650 station-mapped locations (11%). Below this entry.
- 80–90: 921 station-mapped locations (15%). This entry sits in this band.
- 90–100: 564 station-mapped locations (9%). Above this entry.
Source NOAA U.S. Climate Normals, PlainClimate comfort index · 1991–2020
Portland's measured station temperature trend
MethodologyAcross 142 complete annual observations from 1873 to 2025, PORTLAND INTL AP warmed at a fitted rate of 0.10°C per decade. The line shows the fitted change relative to its first year, not raw year-to-year temperatures or a forecast.
- Portland primary station fitted change +0.10 °C/decade
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Snow | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|---|
| January | 48°F (9°C) | 36°F (2°C) | 42°F (5°C) | 5.0" | 1.7" | 8.7 | 0.0 |
| February | 52°F (11°C) | 37°F (3°C) | 44°F (7°C) | 3.7" | 1.2" | 7.2 | 0.0 |
| March | 57°F (14°C) | 40°F (4°C) | 48°F (9°C) | 4.0" | 0.1" | 2.6 | 0.0 |
| April | 62°F (17°C) | 44°F (7°C) | 53°F (12°C) | 2.9" | 0.0" | 0.3 | 0.0 |
| May | 69°F (21°C) | 49°F (10°C) | 59°F (15°C) | 2.5" | 0.0" | 0.0 | 0.4 |
| June | 74°F (24°C) | 54°F (12°C) | 64°F (18°C) | 1.6" | 0.0" | 0.0 | 1.8 |
| July | 82°F (28°C) | 59°F (15°C) | 70°F (21°C) | 0.5" | 0.0" | 0.0 | 5.0 |
| August | 82°F (28°C) | 59°F (15°C) | 71°F (21°C) | 0.5" | 0.0" | 0.0 | 5.3 |
| September | 77°F (25°C) | 54°F (12°C) | 65°F (19°C) | 1.5" | 0.0" | 0.0 | 2.1 |
| October | 64°F (18°C) | 47°F (8°C) | 56°F (13°C) | 3.4" | 0.0" | 0.4 | 0.0 |
| November | 54°F (12°C) | 41°F (5°C) | 47°F (8°C) | 5.5" | 0.0" | 4.1 | 0.0 |
| December | 47°F (8°C) | 36°F (2°C) | 42°F (5°C) | 5.8" | 1.2" | 8.4 | 0.0 |
The year, day by day
The calendar barely moves in Portland: no date carries a normal high of 90°F or a normal low at freezing. The year runs between 36°F near December 21 and 84°F near July 26.
No freezing date
Not one calendar date in the 1991–2020 record carries a normal low at or below 32°F. The coldest normal low of the year is 36°F around December 21.
Where the wet dates fall
The likeliest wet date is December 19, when 63% of years recorded at least a hundredth of an inch. The driest is July 31 at 10%. Summed across the calendar, that is about 157 wet dates a year.
The widest day
July 24 carries the biggest normal gap between afternoon and dawn, 24°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Portland.
Monthly Precipitation
Average monthly rainfall and snowfall
Snow: 1.7"
18.7 days with precipitation
Snow: 1.2"
15.7 days with precipitation
Snow: 0.1"
17.8 days with precipitation
17.4 days with precipitation
13.2 days with precipitation
9.2 days with precipitation
3.7 days with precipitation
3.6 days with precipitation
6.7 days with precipitation
13.5 days with precipitation
18.3 days with precipitation
Snow: 1.2"
19.2 days with precipitation
Portland's wet season runs through the cold months
December, January and February carry 39% of the year's precipitation here, while June through August contribute 7%. That is the cool-season-dominant pattern of the West Coast and the higher inland West, where storm tracks swing south in winter and summer turns dry; the thermometer meanwhile shows an unusually narrow 29°F seasonal spread.
- Wettest month
- December, 5.8"
- Driest month
- July, 0.5"
- Wettest three months
- December, November, January (44% of the year)
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A cool-season label means the December-February share reaches 35%. Where snow falls, the monthly figures above report liquid-equivalent precipitation, so a wet winter month is not necessarily a rainy one.
How Portland's precipitation splits across the calendar
About 157 days a year record measurable precipitation here, carrying 36.9" between them, or roughly 0.24 inches on a typical wet day. That sits in the middle band: neither the many-light-days pattern of the Pacific Northwest and the Great Lakes, nor the few-heavy-events pattern of the Gulf and the desert Southwest.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year and say nothing about the heaviest single storm on record.
Snow reaches Portland, but rarely amounts to much
The normals record 4.2 inches of snow a year here, most likely in January. That is a real but marginal amount: enough that snow is part of the local record, not enough to define the winter.
A figure in this range usually reflects a handful of events that melt quickly rather than a season of accumulation; about 3 days a year record any measurable snow at all.
NOAA 1991-2020 normals. An average across thirty years can smooth away a single heavy winter, so a small annual figure does not mean a significant snowfall is impossible.
Frost Dates & Growing Season
First Fall Freeze
November 19
50% probability date
Last Spring Freeze
March 13
50% probability date
Growing Season
251 days
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
4,104
Higher = more heating needed
Cooling Degree Days
508
Higher = more cooling needed
Warmest Month
August
Coldest Month
December
Humidity & Wind
Monthly averages from hourly observations
| Month | Humidity | Wind (mph) | Clear Sky % | Overcast % |
|---|---|---|---|---|
| January | 79% | 8.5 | 13% | 54% |
| February | 74% | 8.1 | 15% | 45% |
| March | 71% | 7.1 | 13% | 43% |
| April | 66% | 6.9 | 13% | 35% |
| May | 66% | 6.6 | 12% | 33% |
| June | 62% | 6.8 | 22% | 22% |
| July | 61% | 7.0 | 34% | 15% |
| August | 62% | 6.2 | 29% | 15% |
| September | 70% | 5.8 | 31% | 25% |
| October | 78% | 6.8 | 18% | 44% |
| November | 80% | 8.8 | 13% | 53% |
| December | 80% | 9.4 | 9% | 60% |
Nationwide similar cities
Other rankable U.S. places outside OR closest to Portland on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (55°F here).
- Atlantic City, NJ 55°F · 0.0°F off
- Bluff, UT 55°F · 0.0°F off
- Mound City, KS 55°F · 0.0°F off
- Nashville, IL 55°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (36.9" here), excluding temperature-peer places.
- Cassoday, KS 36.9" · 0.0" off
- Pontiac, IL 37.0" · 0.0" off
- Rushford, MN 36.9" · 0.0" off
- Chatham, MI 37.0" · 0.0" off
Data-derived climate profile
How Portland's climate pattern fits together
heating led · moderate · low swing
Heating is the larger measured load in Portland, at 4,104 degree days versus 508 for cooling. Unlike a strongly continental record, however, its 29.0°F month-to-month range is compact; persistent cool-season demand matters more than a dramatic summer-to-winter reversal.
The frost-free window extends for about 251 days. That is a long calendar measure, but it is not a forecast and does not combine heat, rainfall, soil, or local elevation into a planting recommendation.
Temperature varies within a narrow 29.0°F band across the normal year. August and December mark the typical warm and cold ends of the calendar. The annual average is 55°F. Monthly rows still matter, but they refine a steady profile rather than reveal two climatic extremes.
Portland's 36.9 inches of annual precipitation falls in PlainClimate's middle band, so “wet” or “dry” is not the leading description. Annual snowfall totals 4.2 inches. Temperature balance and the calendar distribution carry more information than the annual moisture label alone.
These labels group NOAA 1991-2020 normals from Portland's primary station, so the winter figures are a thirty-year average and not a floor: a single hard season can run well below them. Treat each band as a descriptive range for Portland, not an official NOAA class or a year-ahead forecast.
Questions about Portland's climate
How much rain does Portland get? ▼
How much energy does heating and cooling require in Portland? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Portland's primary station: PORTLAND INTL AP (USW00024229). 2 NOAA stations are mapped to the Portland area; the primary station's record is used for consistency. For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The 2024 Census Gazetteer identifies the exact name-and-state match as an incorporated place (GEOID 4159000). Match rule for Portland: exact normalized name + state only, no fuzzy expansion, so nearby differently spelled facilities stay unmatched.
On this page every temperature, precipitation, and derived score for Portland comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.