August is one of the warmer months of the year in Sunnyvale, with average highs near 30.6°C and lows around 12.3°C (mean 21.5°C). It is one of the drier months, averaging 1 mm of rainfall and 61% relative humidity across the period.
August is one of the warmer months of the year in Sunnyvale. Across 45 years of records, the warmest August in Sunnyvale was 2020 — when the month averaged 23.4°C — while the coldest was 2011 at 19.3°C. Typical August days reach 30.6°C with nights near 12.3°C. The long-term August temperature trend is broadly flat.
August is one of the drier months in Sunnyvale, averaging 1 mm of rainfall. The wettest August on record was 1997 with 13 mm, while the driest were 2014, 2016 and 2021, among others at 0 mm.
Relative humidity in Sunnyvale during August averages 61%. The most humid August was 2011 at 69%, and the least humid was 1996 at 54%.
August receives about 5.9 kWh/m²/day of solar energy in Sunnyvale. The sunniest Augusts were 2019, 2022 and 2025, among others at 6.4 kWh/m²/day, and the cloudiest was 1986 at 4.4.
Average wind speed in Sunnyvale during August is 2.5 m/s. The windiest Augusts were 2021, 2024 and 2025, among others at 2.7 m/s, while the calmest was 1987 at 2.1 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 21.5°C | 21.7°C | 21.3°C | 21.0°C | 21.9°C | +0.4°C |
| Avg High | 31.1°C | 31.0°C | 30.6°C | 29.7°C | 30.9°C | -0.2°C |
| Avg Low | 11.8°C | 12.4°C | 12.1°C | 12.2°C | 13.0°C | +1.2°C |
| Avg Rain | 1 mm | 2 mm | 1 mm | 0 mm | 0 mm | -1 mm |
August temperatures in Sunnyvale have risen by about 0.3°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 8.1°C (2011) to a record high of 44.2°C (1998).
Rainfall in August is one of the drier months, averaging 1 mm, with a wettest year of 13 mm.
Daytime highs and overnight lows have shifted differently — highs fell about 0.2°C per decade while lows rose 0.2°C per decade, narrowing the gap between day and night.
One of the best times to visit Sunnyvale
August is one of the best times to visit Sunnyvale. Expect days averaging 30.6°C and nights around 12.3°C (mean 21.5°C) — warmer than Sunnyvale's yearly average — with low rainfall (1 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 | 30.5°C | 21.6°C | 12.8°C | 39.0°C | 10.8°C | 0 mm | 63% | 2.7 m/s | 6.4 |
| 2024 | 29.3°C | 20.9°C | 12.6°C | 37.1°C | 10.2°C | 0 mm | 63% | 2.7 m/s | 6.3 |
| 2023 | 31.9°C | 22.8°C | 13.7°C | 37.8°C | 10.9°C | 0 mm | 61% | 2.5 m/s | 5.9 |
| 2022 | 31.3°C | 21.9°C | 12.6°C | 41.4°C | 9.8°C | 0 mm | 62% | 2.6 m/s | 6.4 |
| 2021 | 30.0°C | 21.0°C | 12.0°C | 40.1°C | 8.7°C | 0 mm | 63% | 2.7 m/s | 5.6 |
| 2020 🔥 | 32.6°C | 23.4°C | 14.3°C | 42.1°C | 10.4°C | 1 mm | 57% | 2.6 m/s | 5.6 |
| 2019 | 31.5°C | 22.4°C | 13.4°C | 40.4°C | 11.3°C | 0 mm | 62% | 2.6 m/s | 6.4 |
| 2018 | 29.6°C | 20.7°C | 11.7°C | 37.0°C | 9.3°C | 0 mm | 63% | 2.6 m/s | 5.5 |
| 2017 | 30.9°C | 22.3°C | 13.7°C | 41.7°C | 9.9°C | 0 mm | 59% | 2.5 m/s | 5.3 |
| 2016 | 29.1°C | 20.3°C | 11.5°C | 35.3°C | 9.8°C | 0 mm | 64% | 2.7 m/s | 5.5 |
| 2015 | 30.1°C | 21.8°C | 13.6°C | 39.3°C | 11.4°C | 1 mm | 64% | 2.5 m/s | 6.1 |
| 2014 | 30.8°C | 21.9°C | 13.1°C | 38.6°C | 10.8°C | 0 mm | 64% | 2.5 m/s | 5.4 |
| 2013 | 29.1°C | 20.7°C | 12.2°C | 39.3°C | 10.0°C | 0 mm | 68% | 2.6 m/s | 6.1 |
| 2012 | 30.3°C | 20.8°C | 11.4°C | 40.3°C | 8.4°C | 0 mm | 61% | 2.7 m/s | 5.7 |
| 2011 ❄️ | 28.0°C | 19.3°C | 10.7°C | 36.1°C | 8.1°C | 0 mm | 69% | 2.7 m/s | 5.7 |
| 2010 | 28.0°C | 19.5°C | 11.0°C | 42.8°C | 8.3°C | 0 mm | 65% | 2.7 m/s | 5.6 |
| 2009 | 30.6°C | 21.4°C | 12.1°C | 39.8°C | 9.0°C | 0 mm | 61% | 2.4 m/s | 6.2 |
| 2008 | 31.1°C | 21.7°C | 12.3°C | 41.2°C | 9.5°C | 0 mm | 62% | 2.6 m/s | 6 |
| 2007 | 31.1°C | 21.7°C | 12.4°C | 40.5°C | 8.9°C | 0 mm | 62% | 2.5 m/s | 6.2 |
| 2006 | 30.2°C | 20.8°C | 11.4°C | 37.9°C | 8.7°C | 0 mm | 63% | 2.4 m/s | 5.8 |
| 2005 | 32.0°C | 22.2°C | 12.5°C | 38.2°C | 9.8°C | 1 mm | 59% | 2.4 m/s | 5.6 |
| 2004 | 30.9°C | 22.0°C | 13.1°C | 40.4°C | 11.2°C | 1 mm | 63% | 2.5 m/s | 5.7 |
| 2003 | 30.3°C | 21.5°C | 12.7°C | 38.7°C | 11.0°C | 6 mm | 64% | 2.4 m/s | 6.4 |
| 2002 | 30.2°C | 21.0°C | 11.9°C | 39.8°C | 8.7°C | 2 mm | 59% | 2.5 m/s | 5.5 |
| 2001 | 29.2°C | 20.3°C | 11.5°C | 38.0°C | 9.7°C | 1 mm | 66% | 2.7 m/s | 6.3 |
| 2000 | 29.9°C | 20.7°C | 11.5°C | 40.1°C | 9.7°C | 2 mm | 63% | 2.6 m/s | 6.2 |
| 1999 | 28.8°C | 20.3°C | 11.9°C | 40.7°C | 9.5°C | 1 mm | 64% | 2.5 m/s | 5.9 |
| 1998 | 33.1°C | 23.2°C | 13.3°C | 44.2°C | 9.4°C | 0 mm | 55% | 2.3 m/s | 5.7 |
| 1997 🌧️ | 30.1°C | 21.4°C | 12.8°C | 41.6°C | 10.7°C | 13 mm | 64% | 2.4 m/s | 6.4 |
| 1996 | 33.2°C | 22.9°C | 12.6°C | 41.4°C | 8.9°C | 3 mm | 54% | 2.3 m/s | 6.1 |
| 1995 | 31.5°C | 21.7°C | 12.0°C | 37.8°C | 8.9°C | 0 mm | 56% | 2.4 m/s | 6.2 |
| 1994 | 30.5°C | 20.8°C | 11.0°C | 38.4°C | 9.4°C | 0 mm | 63% | 2.5 m/s | 6.3 |
| 1993 | 30.8°C | 21.9°C | 13.0°C | 40.0°C | 10.2°C | 0 mm | 58% | 2.4 m/s | 5.8 |
| 1992 | 32.1°C | 22.4°C | 12.6°C | 38.1°C | 9.8°C | 1 mm | 58% | 2.4 m/s | 5.5 |
| 1991 | 28.3°C | 20.1°C | 11.8°C | 36.5°C | 9.8°C | 4 mm | 67% | 2.5 m/s | 5.6 |
| 1990 | 31.3°C | 22.4°C | 13.4°C | 42.8°C | 10.5°C | 1 mm | 58% | 2.4 m/s | 5.9 |
| 1989 | 30.4°C | 20.6°C | 10.7°C | 36.7°C | 8.6°C | 1 mm | 61% | 2.3 m/s | 5.8 |
| 1988 | 31.9°C | 22.2°C | 12.5°C | 37.9°C | 9.8°C | 0 mm | 58% | 2.4 m/s | 5.6 |
| 1987 | 32.4°C | 22.1°C | 11.8°C | 39.3°C | 9.5°C | 0 mm | 54% | 2.1 m/s | 5.4 |
| 1986 | 32.2°C | 21.9°C | 11.6°C | 37.5°C | 9.8°C | 0 mm | 57% | 2.2 m/s | 4.4 |
| 1985 | 29.8°C | 20.6°C | 11.3°C | 35.0°C | 9.2°C | 0 mm | 58% | 2.4 m/s | 5.9 |
| 1984 | 30.8°C | 21.5°C | 12.2°C | 39.0°C | 10.2°C | 1 mm | 59% | 2.5 m/s | 5.9 |
| 1983 | 30.5°C | 21.8°C | 13.0°C | 40.6°C | 10.0°C | 5 mm | 61% | 2.4 m/s | — |
| 1982 | 30.1°C | 21.0°C | 11.8°C | 38.3°C | 9.5°C | 1 mm | 59% | 2.5 m/s | — |
| 1981 | 31.4°C | 21.4°C | 11.4°C | 39.4°C | 9.2°C | 0 mm | 59% | 2.6 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 30.6°C with lows near 12.3°C (mean 21.5°C), based on 45 years of NASA POWER data.
August averages 1 mm of rainfall in Sunnyvale, one of the drier months. The wettest on record was 13 mm in 1997.
The hottest August reached 44.2°C in 1998. The coldest dipped to 8.1°C in 2011.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 0.3°C. Daytime highs moved from 30.5°C to 30.6°C and overnight lows from 11.9°C to 12.7°C over the same span.
August is one of the warmer months of the year in Sunnyvale and one of the drier months, so plan for around 30.6°C daytime highs and 12.3°C at night.
Not quite — August is the 12th coolest month in Sunnyvale, averaging 21.5°C.
For August in Sunnyvale, pack light, breathable clothing and sun protection, with typical highs of 30.6°C and lows of 12.3°C.
Relative humidity in August averages 61% — moderately humid.
Average wind speed in August is 2.5 m/s. The windiest August on record averaged 2.7 m/s (2001).
The wettest August on record was 1997 with 13 mm. On average, August sees 1 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 Sunnyvale 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.
