August is one of the warmer months of the year in Sammamish, with average highs near 22.5°C and lows around 11.9°C (mean 17.2°C). It is one of the drier months, averaging 40 mm of rainfall and 76% relative humidity across the period.
August is one of the warmer months of the year in Sammamish. Across 45 years of records, the warmest August in Sammamish was 1986 — when the month averaged 19.6°C — while the coldest was 1995 at 14.4°C. Typical August days reach 22.5°C with nights near 11.9°C. The long-term trend is warming, about 0.3°C per decade.
August is one of the drier months in Sammamish, averaging 40 mm of rainfall. The wettest August on record was 2004 with 164 mm, while the driest was 2012 at 4 mm.
Relative humidity in Sammamish during August averages 76%. The most humid August was 1999 at 84%, and the least humid was 2015 at 69%.
August receives about 5.4 kWh/m²/day of solar energy in Sammamish. The sunniest August was 1998 at 6.1 kWh/m²/day, and the cloudiest was 1995 at 4.6.
Average wind speed in Sammamish during August is 0.3 m/s. The windiest Augusts were 2022, 2023 and 2024, among others at 0.3 m/s, while the calmest was 2025 at 0.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 17.0°C | 16.9°C | 16.9°C | 17.7°C | 17.8°C | +0.8°C |
| Avg High | 22.4°C | 22.1°C | 22.1°C | 22.9°C | 23.2°C | +0.8°C |
| Avg Low | 11.4°C | 11.8°C | 11.7°C | 12.5°C | 12.3°C | +0.9°C |
| Avg Rain | 35 mm | 46 mm | 46 mm | 33 mm | 39 mm | +4 mm |
August temperatures in Sammamish have risen by about 1.3°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 5.3°C (1995) to a record high of 37.5°C (2020).
Rainfall in August is one of the drier months, averaging 40 mm, with a wettest year of 164 mm.
One of the best times to visit Sammamish
August is one of the best times to visit Sammamish. Expect days averaging 22.5°C and nights around 11.9°C (mean 17.2°C) — warmer than Sammamish's yearly average — with moderate rainfall (40 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 | 21.7°C | 16.3°C | 11.0°C | 36.5°C | 6.2°C | 72 mm | 81% | 0.2 m/s | 5.2 |
| 2024 | 22.9°C | 17.2°C | 11.6°C | 34.7°C | 8.1°C | 73 mm | 80% | 0.3 m/s | 4.8 |
| 2023 | 24.6°C | 19.1°C | 13.7°C | 33.7°C | 8.5°C | 33 mm | 72% | 0.3 m/s | 5.5 |
| 2022 | 25.4°C | 19.5°C | 13.6°C | 35.0°C | 8.7°C | 14 mm | 74% | 0.3 m/s | 5.9 |
| 2021 | 23.0°C | 17.7°C | 12.4°C | 35.0°C | 8.1°C | 25 mm | 75% | 0.3 m/s | 5.3 |
| 2020 | 21.8°C | 16.7°C | 11.5°C | 37.5°C | 7.5°C | 20 mm | 78% | 0.3 m/s | 5.9 |
| 2019 | 23.6°C | 18.3°C | 13.0°C | 31.0°C | 9.9°C | 27 mm | 75% | 0.3 m/s | 5.2 |
| 2018 | 23.5°C | 18.1°C | 12.6°C | 31.8°C | 9.5°C | 18 mm | 71% | 0.3 m/s | 5.2 |
| 2017 | 25.0°C | 19.5°C | 14.0°C | 33.0°C | 9.4°C | 11 mm | 70% | 0.3 m/s | 5.9 |
| 2016 | 22.7°C | 17.6°C | 12.4°C | 30.9°C | 8.6°C | 20 mm | 75% | 0.3 m/s | 5.7 |
| 2015 | 23.7°C | 18.1°C | 12.6°C | 30.6°C | 8.9°C | 56 mm | 69% | 0.3 m/s | 5.4 |
| 2014 | 22.9°C | 18.1°C | 13.4°C | 35.2°C | 10.2°C | 61 mm | 78% | 0.3 m/s | 5.5 |
| 2013 | 22.6°C | 17.7°C | 12.7°C | 29.2°C | 10.0°C | 65 mm | 81% | 0.3 m/s | 5 |
| 2012 | 23.0°C | 17.5°C | 12.1°C | 35.2°C | 7.9°C | 4 mm | 77% | 0.3 m/s | 5.6 |
| 2011 | 20.9°C | 16.2°C | 11.5°C | 33.1°C | 7.8°C | 15 mm | 79% | 0.3 m/s | 5.5 |
| 2010 | 21.0°C | 16.0°C | 11.0°C | 32.8°C | 5.6°C | 51 mm | 80% | 0.3 m/s | 5.3 |
| 2009 | 21.8°C | 16.8°C | 11.8°C | 34.2°C | 6.3°C | 36 mm | 77% | 0.3 m/s | 4.9 |
| 2008 | 22.0°C | 16.8°C | 11.6°C | 34.6°C | 6.5°C | 91 mm | 80% | 0.3 m/s | 4.8 |
| 2007 | 20.4°C | 15.7°C | 10.9°C | 29.8°C | 8.0°C | 36 mm | 80% | 0.3 m/s | 5 |
| 2006 | 22.1°C | 16.7°C | 11.3°C | 29.1°C | 8.4°C | 13 mm | 73% | 0.3 m/s | 5.8 |
| 2005 | 23.2°C | 17.7°C | 12.2°C | 30.0°C | 8.7°C | 21 mm | 73% | 0.3 m/s | 5.8 |
| 2004 🌧️ | 23.7°C | 18.7°C | 13.7°C | 33.7°C | 9.9°C | 164 mm | 77% | 0.3 m/s | 5.1 |
| 2003 | 23.5°C | 17.8°C | 12.2°C | 30.7°C | 9.3°C | 10 mm | 71% | 0.3 m/s | 5.8 |
| 2002 | 21.7°C | 16.5°C | 11.3°C | 32.7°C | 7.9°C | 16 mm | 76% | 0.3 m/s | 5.8 |
| 2001 | 22.0°C | 17.0°C | 11.9°C | 31.6°C | 8.4°C | 52 mm | 79% | 0.3 m/s | 5 |
| 2000 | 20.2°C | 15.4°C | 10.5°C | 26.0°C | 6.1°C | 23 mm | 79% | 0.3 m/s | 5.5 |
| 1999 | 21.5°C | 16.7°C | 11.9°C | 31.0°C | 7.1°C | 50 mm | 84% | 0.3 m/s | 5.1 |
| 1998 | 22.8°C | 17.6°C | 12.3°C | 33.2°C | 8.4°C | 15 mm | 78% | 0.3 m/s | 6.1 |
| 1997 | 23.2°C | 17.9°C | 12.6°C | 28.0°C | 9.8°C | 38 mm | 79% | 0.3 m/s | 5.6 |
| 1996 | 22.7°C | 17.2°C | 11.8°C | 33.3°C | 7.8°C | 49 mm | 77% | 0.3 m/s | 5.3 |
| 1995 ❄️ | 19.1°C | 14.4°C | 9.8°C | 24.7°C | 5.3°C | 89 mm | 81% | 0.3 m/s | 4.6 |
| 1994 | 21.7°C | 16.7°C | 11.7°C | 27.9°C | 9.1°C | 20 mm | 77% | 0.3 m/s | 5.1 |
| 1993 | 21.3°C | 16.0°C | 10.8°C | 32.0°C | 6.1°C | 31 mm | 80% | 0.3 m/s | 4.9 |
| 1992 | 23.4°C | 17.7°C | 12.0°C | 31.9°C | 6.6°C | 34 mm | 72% | 0.3 m/s | 5.5 |
| 1991 | 22.1°C | 17.3°C | 12.5°C | 28.8°C | 7.7°C | 62 mm | 82% | 0.3 m/s | 4.9 |
| 1990 | 22.8°C | 17.7°C | 12.5°C | 33.0°C | 8.7°C | 75 mm | 78% | 0.3 m/s | 5.1 |
| 1989 | 20.3°C | 15.6°C | 10.8°C | 26.6°C | 8.2°C | 50 mm | 81% | 0.3 m/s | 5 |
| 1988 | 22.2°C | 16.4°C | 10.6°C | 34.4°C | 6.4°C | 19 mm | 76% | 0.3 m/s | 5.2 |
| 1987 | 23.0°C | 17.3°C | 11.5°C | 35.2°C | 8.1°C | 19 mm | 71% | 0.3 m/s | 5.6 |
| 1986 🔥 | 25.7°C | 19.6°C | 13.5°C | 34.9°C | 10.9°C | 12 mm | 70% | 0.3 m/s | 5.6 |
| 1985 | 21.9°C | 16.0°C | 10.1°C | 30.3°C | 7.2°C | 36 mm | 71% | 0.3 m/s | 5.4 |
| 1984 | 20.6°C | 15.6°C | 10.6°C | 28.2°C | 6.4°C | 32 mm | 78% | 0.3 m/s | 5.3 |
| 1983 | 21.8°C | 16.7°C | 11.7°C | 32.8°C | 8.3°C | 72 mm | 80% | 0.3 m/s | — |
| 1982 | 21.9°C | 16.7°C | 11.4°C | 32.2°C | 6.9°C | 47 mm | 76% | 0.3 m/s | — |
| 1981 | 24.6°C | 18.7°C | 12.7°C | 36.4°C | 7.6°C | 29 mm | 73% | 0.3 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 22.5°C with lows near 11.9°C (mean 17.2°C), based on 45 years of NASA POWER data.
August averages 40 mm of rainfall in Sammamish, one of the drier months. The wettest on record was 164 mm in 2004.
The hottest August reached 37.5°C in 2020. The coldest dipped to 5.3°C in 1995.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 1.3°C. Daytime highs moved from 22.2°C to 23.5°C and overnight lows from 11.3°C to 12.5°C over the same span.
August is one of the warmer months of the year in Sammamish and one of the drier months, so plan for around 22.5°C daytime highs and 11.9°C at night.
Not quite — August is the 12th coolest month in Sammamish, averaging 17.2°C.
For August in Sammamish, pack light layers you can adjust through the day, with typical highs of 22.5°C and lows of 11.9°C.
Relative humidity in August averages 76% — quite humid.
Average wind speed in August is 0.3 m/s. The windiest August on record averaged 0.3 m/s (1981).
The wettest August on record was 2004 with 164 mm. On average, August sees 40 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 Sammamish 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.
