Portland, OR climate: monthly averages and frost dates
Portland, OR has cool winters and warm summers by this site's scale, with moderate annual precipitation. The figures are the 1991–2020 climate normals for NOAA station USW00024229 (PORTLAND INTL AP), 4 mi (7 km) in a straight line from the city's center point (US Census).
- Warmest month high
- 82.3°F
- August
- Coldest month mean
- 41.6°F
- December
- Precipitation
- 36.9 in
- per year
- Snowfall
- 4.2 in
- per year
- Median last frost
- March 13
- 32°F, spring
- Median first frost
- November 19
- 32°F, autumn
Monthly averages in Portland
| Month | High °F | Low °F | Mean °F | Precip. in | Snow in | Days ≥0.01 in | Days ≥90°F | Nights ≤32°F |
|---|---|---|---|---|---|---|---|---|
| January | 47.5 | 36.2 | 41.9 | 5.03 | 1.7 | 18.7 | 0.0 | 8.7 |
| February | 51.5 | 36.8 | 44.1 | 3.68 | 1.2 | 15.7 | 0.0 | 7.2 |
| March | 56.8 | 39.7 | 48.3 | 3.97 | 0.1 | 17.8 | 0.0 | 2.6 |
| April | 62.0 | 43.7 | 52.8 | 2.89 | 0.0 | 17.4 | 0.0 | 0.3 |
| May | 69.3 | 49.4 | 59.4 | 2.51 | 0.0 | 13.2 | 0.4 | 0.0 |
| June | 74.3 | 54.1 | 64.2 | 1.63 | 0.0 | 9.2 | 1.8 | 0.0 |
| July | 81.9 | 58.5 | 70.2 | 0.51 | 0.0 | 3.7 | 5.0 | 0.0 |
| August | 82.3 | 58.9 | 70.6 | 0.54 | 0.0 | 3.6 | 5.3 | 0.0 |
| September | 76.7 | 54.1 | 65.4 | 1.52 | 0.0 | 6.7 | 2.1 | 0.0 |
| October | 64.4 | 46.7 | 55.6 | 3.42 | 0.0 | 13.5 | 0.0 | 0.4 |
| November | 53.5 | 40.6 | 47.1 | 5.45 | 0.0 | 18.3 | 0.0 | 4.1 |
| December | 46.9 | 36.2 | 41.6 | 5.77 | 1.2 | 19.2 | 0.0 | 8.4 |
| Year | 63.9 | 46.2 | 55.1 | 36.92 | 4.2 | 157.0 | 14.6 | 31.7 |
How cold is winter in Portland?
Winters in Portland are cool by this site's scale (coldest-month mean 32 to under 45°F). The coldest month is December, with a mean temperature of 41.6°F (5.3°C), a normal daily high of 46.9°F (8.3°C) and a normal daily low of 36.2°F (2.3°C).
The station averages 31.7 nights a year at or below 32°F and 1.6 days when the high stays at or below 32°F.
How hot is summer in Portland?
Summers in Portland are warm by this site's scale (hottest-month high 80 to under 90°F). August has the highest normal daily high, 82.3°F (27.9°C), with nights averaging 58.9°F (14.9°C).
The high reaches 90°F or more on 14.6 days in a normal year.
What is the wettest month in Portland?
Portland gets 36.92 in (938 mm) of precipitation in a normal year, which this site classes as moderate (20 to under 40 in a year). The wettest month is December with 5.77 in (147 mm); the driest is July with 0.51 in (13 mm).
Measurable precipitation (0.01 in or more) falls on 157.0 days a year.
Does it snow in Portland?
Normal annual snowfall in Portland is 4.2 in (11 cm), which this site classes as light (1 to under 12 in a year).
January is the snowiest month, with 1.7 in (4 cm).
A day with 1.0 in or more of snowfall comes 1.4 times a year on average.
Which months are mild in Portland?
5 months in Portland meet this site's comfort thresholds (normal high 65–85°F, low 45°F or higher, fewer than 10 days with 0.10 in or more of precipitation): May to September.
October misses by one threshold only (normal high 64.4°F, below the 65°F limit).
Thresholds and their limits: methodology.
Frost dates and growing season in Portland
In Portland the median last spring night at or below 32°F is March 13, and the median first autumn one is November 19 (NOAA P50 dates). NOAA's median length of the freeze-free season is 247 days. NOAA takes that median over each year's own season, so it need not equal the 251 days between the two median dates.
There is still a 10% chance of a 32°F night on or after April 1, and a 10% chance that the first one has come by October 29.
The chance that the last spring 32°F night comes on or after February 22 is 90%.
For a hard freeze (28°F or lower) the median dates are February 16 in spring and December 5 in autumn.
| Chance | Last spring 32°F night on or after | First autumn 32°F night by | Freeze-free season, days |
|---|---|---|---|
| 10% | April 1 | October 29 | 277 |
| 20% | March 26 | November 5 | 266 |
| 30% | March 21 | November 11 | 260 |
| 40% | March 17 | November 14 | 253 |
| 50% | March 13 | November 19 | 247 |
| 60% | March 9 | November 23 | 242 |
| 70% | March 6 | November 27 | 236 |
| 80% | February 28 | December 2 | 229 |
| 90% | February 22 | December 10 | 219 |
| Threshold | Median last date (spring) | Median first date (autumn or winter) | Median season, days |
|---|---|---|---|
| 36°F | April 6 | November 2 | 210 |
| 32°F | March 13 | November 19 | 247 |
| 28°F | February 16 | December 5 | 298 |
| 24°F | January 13 | December 21 | 342 |
| 20°F | No such night in most years, though a few years have one; no typical season to show | ||
| 16°F | No such night in most years, though a few years have one; no typical season to show | ||
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 96% | 95% | 76% | 11% | 0% | 0% | 0% | 0% | 0% | 14% | 73% | 98% |
Nearby and similar places
Of the places on this site, the closest to Portland by station distance are Seattle, WA at 129 mi (207 km), Spokane, WA at 279 mi (448 km) and Boise, ID at 343 mi (551 km).
Among places whose winter, summer and precipitation words are each within one band of Portland's (winter: cool, summer: warm, precipitation: moderate), the closest monthly temperature and precipitation patterns are Seattle, WA, Boston, MA and San Francisco, CA.
Compared with Seattle, WA, Portland's peak-month normal high is 4.7°F (2.6°C) higher, its coldest-month mean is 0.4°F (0.2°C) lower, and its annual precipitation is 2.42 in less.
| Place | Listed as | Station distance | Coldest mean °F | Warmest high °F | Precip. in/yr | Snow in/yr | Last frost |
|---|---|---|---|---|---|---|---|
| Portland, OR | this page | – | 41.6 | 82.3 | 36.9 | 4.2 | March 13 |
| Seattle, WA | nearby, similar | 129 mi (207 km) | 42.0 | 77.6 | 39.3 | 6.3 | March 2 |
| Spokane, WA | nearby | 279 mi (448 km) | 29.1 | 84.4 | 16.4 | 45.4 | April 26 |
| Boise, ID | nearby | 343 mi (551 km) | 32.1 | 92.7 | 11.5 | 17.6 | April 24 |
| Boston, MA | similar | 2,530 mi (4,072 km) | 29.9 | 82.1 | 43.6 | 49.2 | April 4 |
| San Francisco, CA | similar | 551 mi (887 km) | 51.3 | 74.8 | 19.6 | – | rare freeze |
How nearby and similar places are chosen: methodology.
Source and station
The data for Portland come from NOAA station PORTLAND INTL AP, OR US (USW00024229) at 45.5908, -122.6003, elevation 19 ft (6 m). It lies 4 mi (7 km) in a straight line from the center point of Portland city, the “internal point” in the US Census 2024 Gazetteer.
Each monthly normal used here rests on at least 27 years of data from 1991–2020 (NOAA's per-field year counts).
NOAA completeness flags on the monthly fields used here:
- S: Standard: meets WMO standards for data availability for 24 or more years.
Cite the data as:
Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020). Station USW00024229 (PORTLAND INTL AP, OR US). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/wck8-er13. Accessed 2026-10-09.
Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Annual/Seasonal Climate Normals (1991-2020). Station USW00024229 (PORTLAND INTL AP, OR US). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/4ek7-fk11. Accessed 2026-10-09.
Files used: monthly normals CSV, annual/seasonal normals CSV (retrieved 2026-10-09). The values on this page as JSON: /us/or/portland/data.json.