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Portland, Oregon climate
Csb Warm-summer Mediterranean
Portland has a seasonal mild-temperate climate (Warm-summer Mediterranean, Köppen Csb). The hottest month is August with an average daily high near 82°F, while the coldest is December averaging around 36°F at night. Precipitation totals about 37 inches a year and is strongly seasonal — December alone averages 5.8 inches while July barely receives 0.51 inches. Snow is occasional (4 inches of snow per year on average).
Temperature & precipitation
Daily high–low temperature range with the monthly average, plus monthly precipitation · 1991–2020 normals · hover a month for the exact figuresHours of sunshine per day
Estimated sunny hours each month — daylight length × clear-sky fraction · 1991–2020 monthly cloud cover (NASA POWER)Portland climate normals (1991–2020)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 48 | 52 | 57 | 62 | 69 | 74 | 82 | 82 | 77 | 64 | 54 | 47 |
| Avg temp (°F) | 42 | 44 | 48 | 53 | 59 | 64 | 70 | 71 | 65 | 56 | 47 | 42 |
| Avg low (°F) | 36 | 37 | 40 | 44 | 49 | 54 | 59 | 59 | 54 | 47 | 41 | 36 |
| Precipitation (in) | 5.0 | 3.7 | 4.0 | 2.9 | 2.5 | 1.6 | 0.5 | 0.5 | 1.5 | 3.4 | 5.5 | 5.8 |
| Snowfall (in) | 1.7 | 1.2 | 0.1 | — | — | — | — | — | — | — | — | 1.2 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Avg high (°F) | 48 | 52 | 57 | 62 | 69 | 74 |
| Avg temp (°F) | 42 | 44 | 48 | 53 | 59 | 64 |
| Avg low (°F) | 36 | 37 | 40 | 44 | 49 | 54 |
| Precipitation (in) | 5.0 | 3.7 | 4.0 | 2.9 | 2.5 | 1.6 |
| Snowfall (in) | 1.7 | 1.2 | 0.1 | — | — | — |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Avg high (°F) | 82 | 82 | 77 | 64 | 54 | 47 |
| Avg temp (°F) | 70 | 71 | 65 | 56 | 47 | 42 |
| Avg low (°F) | 59 | 59 | 54 | 47 | 41 | 36 |
| Precipitation (in) | 0.5 | 0.5 | 1.5 | 3.4 | 5.5 | 5.8 |
| Snowfall (in) | — | — | — | — | — | 1.2 |
Sky & atmosphere
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cloud cover (%) | 76 | 74 | 76 | 75 | 70 | 64 | 43 | 43 | 49 | 63 | 75 | 78 |
| Relative humidity (%) | 92 | 89 | 87 | 84 | 82 | 80 | 72 | 66 | 68 | 79 | 89 | 92 |
| Wind speed (mph) | 1.8 | 1.8 | 1.8 | 1.7 | 1.6 | 1.6 | 1.6 | 1.7 | 1.6 | 1.7 | 1.8 | 1.8 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 76 | 74 | 76 | 75 | 70 | 64 |
| Relative humidity (%) | 92 | 89 | 87 | 84 | 82 | 80 |
| Wind speed (mph) | 1.8 | 1.8 | 1.8 | 1.7 | 1.6 | 1.6 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Cloud cover (%) | 43 | 43 | 49 | 63 | 75 | 78 |
| Relative humidity (%) | 72 | 66 | 68 | 79 | 89 | 92 |
| Wind speed (mph) | 1.6 | 1.7 | 1.6 | 1.7 | 1.8 | 1.8 |
30-year delta table (1991–2020 minus 1981–2010, °F)
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Δ Max temp | +0.5 | +0.2 | +0.1 | +0.6 | +1.3 | +0.8 | +1.3 | +1.2 | +0.9 | +0.6 | +0.7 | +1.3 |
| Δ Avg temp | +0.5 | +0.3 | +0.1 | +0.5 | +1.1 | +0.6 | +1.0 | +1.1 | +0.9 | +0.7 | +0.5 | +1.2 |
| Δ Min temp | +0.4 | +0.5 | +0.1 | +0.6 | +0.8 | +0.5 | +0.7 | +0.9 | +1.0 | +0.7 | +0.1 | +1.0 |
| Jan – Jun | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|
| Δ Max temp | +0.5 | +0.2 | +0.1 | +0.6 | +1.3 | +0.8 |
| Δ Avg temp | +0.5 | +0.3 | +0.1 | +0.5 | +1.1 | +0.6 |
| Δ Min temp | +0.4 | +0.5 | +0.1 | +0.6 | +0.8 | +0.5 |
| Jul – Dec | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|
| Δ Max temp | +1.3 | +1.2 | +0.9 | +0.6 | +0.7 | +1.3 |
| Δ Avg temp | +1.0 | +1.1 | +0.9 | +0.7 | +0.5 | +1.2 |
| Δ Min temp | +0.7 | +0.9 | +1.0 | +0.7 | +0.1 | +1.0 |
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Portland Intl AP (NOAA GHCN station USW00024229), about 10 km from the city centre.
Cloud, humidity, wind & sunshine — modelled estimates from NASA POWER, NASA's satellite-and-reanalysis climatology. This is the standard global source for atmospheric variables, which are not measured at most weather stations.