August is one of the warmer months of the year in Portland, with average highs near 20.7°C and lows around 16.9°C (mean 18.8°C). It is one of the drier months, averaging 86 mm of rainfall and 85% relative humidity across the period.
August is one of the warmer months of the year in Portland. Across 45 years of records, the warmest August in Portland was 2022 — when the month averaged 20.7°C — while the coldest was 1982 at 17.1°C. Typical August days reach 20.7°C with nights near 16.9°C. The long-term trend is warming, about 0.5°C per decade.
August is one of the drier months in Portland, averaging 86 mm of rainfall. The wettest August on record was 1991 with 270 mm, while the driest was 1996 at 12 mm.
Relative humidity in Portland during August averages 85%. The most humid Augusts were 2008 and 2009 at 89%, and the least humid was 2025 at 79%.
August receives about 5.2 kWh/m²/day of solar energy in Portland. The sunniest Augusts were 2002 and 2025 at 5.8 kWh/m²/day, and the cloudiest were 2003 and 2023 at 4.7.
Average wind speed in Portland during August is 2.5 m/s. The windiest August was 2023 at 3 m/s, while the calmest was 1984 at 2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 18.0°C | 18.3°C | 18.8°C | 19.4°C | 19.9°C | +1.9°C |
| Avg High | 20.0°C | 20.2°C | 20.5°C | 21.2°C | 21.7°C | +1.7°C |
| Avg Low | 16.0°C | 16.4°C | 17.0°C | 17.6°C | 18.1°C | +2.1°C |
| Avg Rain | 78 mm | 83 mm | 84 mm | 103 mm | 75 mm | -3 mm |
August temperatures in Portland have risen by about 1.8°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 9.3°C (1982) to a record high of 26.4°C (2010).
Rainfall in August is one of the drier months, averaging 86 mm, with a wettest year of 270 mm.
One of the best times to visit Portland
August is one of the best times to visit Portland. Expect days averaging 20.7°C and nights around 16.9°C (mean 18.8°C) — warmer than Portland's yearly average — with higher rainfall (86 mm), so conditions are generally comfortable for sightseeing and outdoor plans.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 21.5°C | 19.4°C | 17.3°C | 25.7°C | 14.2°C | 29 mm | 79% | 2.7 m/s | 5.8 |
| 2024 | 21.1°C | 19.4°C | 17.7°C | 25.1°C | 15.3°C | 115 mm | 87% | 2.3 m/s | 4.9 |
| 2023 | 20.8°C | 19.2°C | 17.6°C | 23.4°C | 15.0°C | 120 mm | 87% | 3 m/s | 4.7 |
| 2022 🔥 | 22.5°C | 20.7°C | 18.9°C | 26.3°C | 16.7°C | 64 mm | 85% | 2.5 m/s | 5.3 |
| 2021 | 22.1°C | 20.3°C | 18.5°C | 26.0°C | 15.9°C | 57 mm | 86% | 2.3 m/s | 4.8 |
| 2020 | 22.2°C | 20.3°C | 18.4°C | 25.5°C | 13.9°C | 64 mm | 82% | 2.9 m/s | 5.3 |
| 2019 | 21.2°C | 19.4°C | 17.5°C | 24.7°C | 14.5°C | 195 mm | 86% | 2.5 m/s | 5.6 |
| 2018 | 22.3°C | 20.6°C | 19.0°C | 25.4°C | 16.5°C | 70 mm | 87% | 2.5 m/s | 5.1 |
| 2017 | 20.5°C | 18.7°C | 16.9°C | 22.8°C | 13.8°C | 62 mm | 84% | 2.4 m/s | 5.4 |
| 2016 | 22.4°C | 20.4°C | 18.3°C | 25.3°C | 15.6°C | 76 mm | 82% | 2.6 m/s | 5.6 |
| 2015 | 21.4°C | 19.7°C | 18.0°C | 23.7°C | 16.0°C | 82 mm | 87% | 2.2 m/s | 5.4 |
| 2014 | 20.3°C | 18.6°C | 16.8°C | 23.2°C | 14.3°C | 117 mm | 87% | 2.3 m/s | 5.4 |
| 2013 | 20.6°C | 18.6°C | 16.7°C | 23.1°C | 14.3°C | 73 mm | 85% | 2.4 m/s | 5.6 |
| 2012 | 21.9°C | 20.3°C | 18.6°C | 24.0°C | 15.9°C | 121 mm | 87% | 2.4 m/s | 5.4 |
| 2011 | 20.6°C | 18.9°C | 17.2°C | 23.2°C | 14.8°C | 160 mm | 88% | 2.7 m/s | 4.9 |
| 2010 | 21.2°C | 19.3°C | 17.4°C | 26.4°C | 14.7°C | 78 mm | 84% | 2.7 m/s | 5.4 |
| 2009 | 21.0°C | 19.4°C | 17.8°C | 24.3°C | 13.1°C | 123 mm | 89% | 2.6 m/s | 5.5 |
| 2008 | 19.7°C | 18.1°C | 16.5°C | 21.6°C | 14.2°C | 126 mm | 89% | 2.5 m/s | 4.9 |
| 2007 | 20.3°C | 18.4°C | 16.5°C | 23.6°C | 12.1°C | 81 mm | 85% | 2.4 m/s | 5.4 |
| 2006 | 20.1°C | 18.4°C | 16.6°C | 25.1°C | 13.2°C | 76 mm | 86% | 2.6 m/s | 5.1 |
| 2005 | 20.9°C | 19.1°C | 17.3°C | 23.5°C | 15.0°C | 79 mm | 88% | 2.4 m/s | 5.2 |
| 2004 | 19.6°C | 18.0°C | 16.3°C | 22.5°C | 13.8°C | 140 mm | 88% | 2.5 m/s | 5.1 |
| 2003 | 20.7°C | 18.9°C | 17.1°C | 24.6°C | 12.8°C | 71 mm | 86% | 2.3 m/s | 4.7 |
| 2002 | 21.8°C | 19.7°C | 17.7°C | 25.7°C | 13.4°C | 47 mm | 79% | 2.4 m/s | 5.8 |
| 2001 | 21.5°C | 19.6°C | 17.6°C | 26.2°C | 14.6°C | 31 mm | 82% | 2.4 m/s | 5.3 |
| 2000 | 19.7°C | 18.0°C | 16.3°C | 22.4°C | 13.3°C | 63 mm | 86% | 2.4 m/s | 5 |
| 1999 | 20.6°C | 18.6°C | 16.5°C | 25.1°C | 13.4°C | 58 mm | 82% | 2.6 m/s | 5.1 |
| 1998 | 20.3°C | 18.6°C | 16.9°C | 22.4°C | 13.6°C | 91 mm | 87% | 2.3 m/s | 5.3 |
| 1997 | 19.7°C | 17.9°C | 16.1°C | 23.7°C | 15.0°C | 104 mm | 85% | 2.3 m/s | 5.1 |
| 1996 | 19.9°C | 18.0°C | 16.1°C | 22.2°C | 13.8°C | 12 mm | 86% | 2.2 m/s | 5.4 |
| 1995 | 20.8°C | 18.6°C | 16.4°C | 24.4°C | 13.8°C | 26 mm | 79% | 2.7 m/s | 5.4 |
| 1994 | 20.1°C | 18.1°C | 16.1°C | 23.5°C | 12.9°C | 76 mm | 83% | 2.7 m/s | 5.2 |
| 1993 | 20.2°C | 18.4°C | 16.5°C | 24.9°C | 13.3°C | 41 mm | 84% | 2.3 m/s | 5.7 |
| 1992 | 19.1°C | 17.3°C | 15.5°C | 22.0°C | 13.0°C | 72 mm | 85% | 2.6 m/s | 5 |
| 1991 🌧️ | 20.5°C | 18.5°C | 16.5°C | 24.5°C | 13.3°C | 270 mm | 86% | 2.7 m/s | 5 |
| 1990 | 21.2°C | 19.3°C | 17.4°C | 24.7°C | 13.1°C | 83 mm | 84% | 2.3 m/s | 5.1 |
| 1989 | 19.8°C | 18.0°C | 16.2°C | 22.2°C | 11.8°C | 62 mm | 85% | 2.7 m/s | 5.2 |
| 1988 | 20.6°C | 18.7°C | 16.8°C | 24.5°C | 12.0°C | 133 mm | 86% | 2.5 m/s | 4.8 |
| 1987 | 19.6°C | 17.5°C | 15.4°C | 24.0°C | 12.0°C | 52 mm | 80% | 2.7 m/s | 5.4 |
| 1986 | 19.4°C | 17.5°C | 15.7°C | 21.8°C | 10.5°C | 61 mm | 84% | 2.9 m/s | 5 |
| 1985 | 19.7°C | 17.7°C | 15.7°C | 24.1°C | 11.7°C | 103 mm | 82% | 2.7 m/s | 4.8 |
| 1984 | 20.5°C | 18.7°C | 16.9°C | 23.9°C | 13.4°C | 55 mm | 88% | 2 m/s | 5.4 |
| 1983 | 20.5°C | 18.2°C | 15.9°C | 23.9°C | 12.7°C | 92 mm | 83% | 2.4 m/s | — |
| 1982 ❄️ | 19.1°C | 17.1°C | 15.1°C | 22.7°C | 9.3°C | 78 mm | 83% | 2.8 m/s | — |
| 1981 | 20.6°C | 18.5°C | 16.3°C | 22.9°C | 13.4°C | 62 mm | 82% | 2.6 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 20.7°C with lows near 16.9°C (mean 18.8°C), based on 45 years of NASA POWER data.
August averages 86 mm of rainfall in Portland, one of the drier months. The wettest on record was 270 mm in 1991.
The hottest August reached 26.4°C in 2010. The coldest dipped to 9.3°C in 1982.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 1.8°C. Daytime highs moved from 20.1°C to 21.6°C and overnight lows from 16°C to 18°C over the same span.
August is one of the warmer months of the year in Portland and one of the drier months, so plan for around 20.7°C daytime highs and 16.9°C at night.
Not quite — August is the 12th coolest month in Portland, averaging 18.8°C.
For August in Portland, pack light layers you can adjust through the day, with typical highs of 20.7°C and lows of 16.9°C. Bring an umbrella or light rain jacket too.
Relative humidity in August averages 85% — quite humid.
Average wind speed in August is 2.5 m/s. The windiest August on record averaged 3 m/s (2023).
The wettest August on record was 1991 with 270 mm. On average, August sees 86 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Portland behaves each August, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for August specifically, along with year-by-year records and how the month has changed over the decades.
