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Portland vs Seattle weather: climate comparison
Portland is the warmer of the two, averaging 54°F (12°C) over the year against 52°F (11°C) in Seattle. Portland is wetter, with 50.4 in (1280 mm) of precipitation a year to Seattle's 50.2 in (1275 mm). Below: every month side by side, from 30 years of ERA5 data (1996–2025).
- Mean temperature
- 12.0°C Portland
10.9°C Seattle - Annual precipitation
- 1279.7 mm Portland
1274.6 mm Seattle - Rainy days a year
- 146 Portland
154 Seattle - Sunshine per day
- 8.5 h Portland
8.3 h Seattle
Month by month
| Month | Portland | Seattle |
|---|---|---|
| January | 8.1°C | 7.3°C |
| February | 9.5°C | 8.4°C |
| March | 12.0°C | 10.6°C |
| April | 14.8°C | 13.4°C |
| May | 18.6°C | 16.9°C |
| June | 22.2°C | 20.0°C |
| July | 27.6°C | 24.0°C |
| August | 27.9°C | 24.2°C |
| September | 23.9°C | 20.4°C |
| October | 16.8°C | 14.6°C |
| November | 11.0°C | 9.8°C |
| December | 7.7°C | 6.9°C |
Year at a glance
| Measure | Portland | Seattle |
|---|---|---|
| Mean annual temperature | 12.0°C | 10.9°C |
| Warmest month (avg high) | Aug · 28°C | Aug · 24°C |
| Coldest month (avg low) | Feb · 2°C | Feb · 2°C |
| Annual range (warmest high − coldest low) | 26°C | 22°C |
| Annual precipitation | 1279.7 mm | 1274.6 mm |
| Rainy days per year | 146 | 154 |
| Wettest / driest month | Dec / Jul | Nov / Jul |
| Average sunshine per day | 8.5 h | 8.3 h |
In short: Portland is the warmest overall (12.0°C mean); Portland gets the most precipitation (1279.7 mm a year); Portland is the sunniest (8.5 h a day on average); Seattle has the smallest swing between its warmest and coldest months.
Record high 1996–2025: Portland 46.0°C (2021-06-28), Seattle 37.9°C (2021-06-28). Record low: Portland -15.3°C (1996-02-02), Seattle -14.5°C (1996-01-30).
Source: Open-Meteo Historical Weather API (CC BY 4.0). Values are ERA5 reanalysis model data on a ~9–25 km grid, not readings from a weather station, so a single town’s thermometer can differ by a few degrees and local showers can be missed. Monthly means of daily ERA5 values, 1996–2025, for the grid cells nearest Portland (45.52, -122.64) and Seattle (47.63, -122.32).
Which months differ most?
The gap in average highs is widest in August, when Portland runs 7°F / 4°C warmer, and narrowest in December (1°F / 1°C apart). The biggest rainfall difference is in December: Portland gets 1.1 in (27 mm) more on average.
Add a third or fourth city, or swap in any other place, in the full comparison tool. For one city in depth, see the Portland climate and Seattle climate pages.
Compare Portland or Seattle with another city
Questions people ask
Is Portland warmer than Seattle?
Portland is warmer on average: its mean annual temperature is 54°F (12°C) against 52°F (11°C) in Seattle (ERA5, 1996–2025).
Which gets more rain, Portland or Seattle?
Portland, with about 50.4 in (1280 mm) of precipitation a year and 146 days with at least 1 mm, compared with 50.2 in (1275 mm) and 154 days in Seattle.
Which is sunnier, Portland or Seattle?
Portland averages more sunshine: 8.5 h a day against 8.3 h. Sunshine duration is modelled from cloud cover.
How reliable is this comparison?
Both cities use the same 30-year reanalysis, so differences are consistent. Absolute values describe a grid cell several kilometres wide and can differ by a degree or two from the airport station.