Portland weather in August
In August, Portland has daytime highs averaging 29 °C, nights around 15 °C, with 2.7 wet days. Figures are 1991–2020 climate normals.
- 28.8°C Average high
- 14.5°C Average low
- 2.7days Wet days
- 15mm Rainfall
- 14h Daylight
Daily temperatures through August
How August develops
Averages for the first, middle and last part of the month, from daily 1991–2020 normals. Chance of rain is the share of years in which that calendar day recorded more than 1 mm.
| Days | Avg high | Avg low | Chance of rain |
|---|---|---|---|
| 1–10 August | 29.2 °C | 14.7 °C | 6 % |
| 11–20 August | 29.6 °C | 14.9 °C | 7 % |
| 21–31 August | 27.8 °C | 14.0 °C | 13 % |
- Average highs fall from 29.2 °C early in August to 27.8 °C by the end of it.
- Rain is most likely over days 21–31 of August (13 % of days) and least likely over days 1–10 (6 %).
What to expect
| Measure | Typical August | Share of the month |
|---|---|---|
| Days above 25 °C | 25 of 31 | 81 % |
| Days above 30 °C | 12 of 31 | 39 % |
| Days below 0 °C | 0 of 31 | 0 % |
| Days with more than 1 mm rain | 2.7 of 31 | 9 % |
Conditions in August
| Measure | Average |
|---|---|
| Mean temperature | 21 °C |
| Record high (1991–2020) | 40 °C |
| Record low (1991–2020) | 9.0 °C |
| Relative humidity | 60 % |
| Wind speed | 12 km/h |
| Cloud cover | 35 % |
Where Portland ranks in August
| Ranking | Position | Value |
|---|---|---|
| Places with the best weather in North America in August | 35thof 50 | 85/100 |
| The driest places in North America in August | 46thof 50 | 15 mm |
August compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| June | 23.0 °C | 46 mm | 58 % |
| July | 28.2 °C | 13 mm | 36 % |
| August | 28.8 °C | 15 mm | 35 % |
| September | 25.2 °C | 44 mm | 42 % |
| October | 17.7 °C | 107 mm | 60 % |
See all twelve months for Portland
- August is the warmest month in Portland.
- It is the 2nd driest month of the year.
- It ranks 1st for least cloud cover.
- Days last about 14 hours from sunrise to sunset.
- It rains on 2.7 of 31 days — 9 % of the month.
- Nights are about 14 °C cooler than the middle of the day.
- The hottest August day on record since 1991 reached 40 °C, 11 °C above the usual daytime high.
Nearby destinations in August
| Destination | Avg high | Wet days |
|---|---|---|
| Portland | 29 °C | 2.7 |
| Vancouver | 28 °C | 3 |
| Salem | 29 °C | 2 |
| Eugene | 29 °C | 2 |
| Tacoma | 25 °C | 4 |
QuestionsAugust in Portland, answered
How warm is Portland in August?
Daily highs average 29 °C and nights fall to about 15 °C, a spread of 14 °C between afternoon and dawn. That makes August the 1st warmest month of the year here.
Does it rain much in Portland in August?
August averages 15 mm of rain, spread over about 3 of the 31 days — 9 % of the month. Cloud cover averages 35 % of the sky.
How long are the days in August?
Portland averages 14 hours between sunrise and sunset in August. Day length is computed from latitude and date, so it is exact rather than modelled — but it says nothing about how much of that time is sunny.
Data sources and method
- ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
- Open-Meteo — Open-Meteo.com. CC BY 4.0
- NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
- GeoNames — GeoNames.org. CC BY 4.0
- Normal period
- 1991–2020
- Dataset version
- era5-1991-2020-scores1.1
- Last processed
Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: daylight hours, beach and comfort scores, monthly rankings, threshold day counts, chance of a wet day by date, ten-day averages within the month. Full formulas are on the methodology page.
Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.