August is one of the warmer months of the year in San Bernardino, with average highs near 34.6°C and lows around 18.5°C (mean 26.6°C). It is one of the drier months, averaging 7 mm of rainfall and 39% relative humidity across the period.
August is one of the warmer months of the year in San Bernardino. Across 45 years of records, the warmest August in San Bernardino was 2012 — when the month averaged 28.6°C — while the coldest was 1989 at 24°C. Typical August days reach 34.6°C with nights near 18.5°C. The long-term trend is warming, about 0.2°C per decade.
August is one of the drier months in San Bernardino, averaging 7 mm of rainfall. The wettest August on record was 2023 with 73 mm, while the driest were 1985, 2002 and 2019 at 0 mm.
Relative humidity in San Bernardino during August averages 39%. The most humid August was 1983 at 47%, and the least humid was 1981 at 29%.
August receives about 7.2 kWh/m²/day of solar energy in San Bernardino. The sunniest August was 2006 at 7.8 kWh/m²/day, and the cloudiest was 1984 at 6.2.
Average wind speed in San Bernardino during August is 1.7 m/s. The windiest August was 1989 at 1.9 m/s, while the calmest were 2011, 2012 and 2019, among others at 1.6 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 26.2°C | 26.5°C | 26.4°C | 26.5°C | 27.4°C | +1.2°C |
| Avg High | 34.2°C | 34.6°C | 34.5°C | 34.6°C | 35.4°C | +1.2°C |
| Avg Low | 18.2°C | 18.4°C | 18.4°C | 18.5°C | 19.5°C | +1.3°C |
| Avg Rain | 11 mm | 4 mm | 5 mm | 4 mm | 15 mm | +4 mm |
August temperatures in San Bernardino have risen by about 0.6°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 9.8°C (1990) to a record high of 43.3°C (1997).
Rainfall in August is one of the drier months, averaging 7 mm, with a wettest year of 73 mm.
A good time to visit San Bernardino
August is a good time to visit San Bernardino, with days averaging 34.6°C and nights around 18.5°C (mean 26.6°C, warmer than San Bernardino's yearly average) and low rainfall. June and October are marginally more temperate, but August still suits most travellers.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 35.9°C | 27.5°C | 19.1°C | 41.2°C | 14.1°C | 4 mm | 33% | 1.7 m/s | 7.2 |
| 2024 | 34.9°C | 27.0°C | 19.1°C | 39.9°C | 12.5°C | 1 mm | 35% | 1.7 m/s | 7.4 |
| 2023 🌧️ | 34.0°C | 26.5°C | 19.1°C | 40.2°C | 15.7°C | 73 mm | 42% | 1.8 m/s | 6.9 |
| 2022 | 36.1°C | 28.5°C | 20.9°C | 43.3°C | 16.8°C | 5 mm | 37% | 1.7 m/s | 7 |
| 2021 | 34.5°C | 26.8°C | 19.1°C | 40.6°C | 14.9°C | 3 mm | 39% | 1.8 m/s | 7.2 |
| 2020 | 36.7°C | 28.3°C | 19.9°C | 43.0°C | 13.5°C | 2 mm | 37% | 1.8 m/s | 7.2 |
| 2019 | 35.2°C | 26.9°C | 18.5°C | 39.8°C | 14.8°C | 0 mm | 31% | 1.6 m/s | 7.7 |
| 2018 | 35.0°C | 26.9°C | 18.8°C | 40.1°C | 13.5°C | 2 mm | 40% | 1.8 m/s | 7.4 |
| 2017 | 34.5°C | 26.9°C | 19.3°C | 42.5°C | 13.7°C | 6 mm | 40% | 1.7 m/s | 7 |
| 2016 | 34.7°C | 26.3°C | 18.0°C | 40.2°C | 14.1°C | 1 mm | 36% | 1.7 m/s | 7.6 |
| 2015 | 34.9°C | 26.9°C | 18.8°C | 41.4°C | 13.1°C | 0 mm | 40% | 1.7 m/s | 7.4 |
| 2014 | 33.2°C | 25.5°C | 17.8°C | 38.8°C | 14.1°C | 11 mm | 42% | 1.7 m/s | 7.3 |
| 2013 | 33.7°C | 26.0°C | 18.3°C | 37.7°C | 11.5°C | 6 mm | 36% | 1.7 m/s | 7.3 |
| 2012 🔥 | 36.4°C | 28.6°C | 20.9°C | 41.3°C | 13.8°C | 9 mm | 35% | 1.6 m/s | 6.9 |
| 2011 | 34.9°C | 26.3°C | 17.7°C | 42.0°C | 13.3°C | 2 mm | 34% | 1.6 m/s | 7.6 |
| 2010 | 33.5°C | 25.1°C | 16.8°C | 41.7°C | 10.8°C | 2 mm | 36% | 1.7 m/s | 7.6 |
| 2009 | 34.8°C | 26.5°C | 18.2°C | 40.9°C | 13.4°C | 0 mm | 35% | 1.7 m/s | 7.4 |
| 2008 | 35.1°C | 26.8°C | 18.6°C | 39.0°C | 14.6°C | 2 mm | 39% | 1.7 m/s | 7.3 |
| 2007 | 35.3°C | 27.3°C | 19.3°C | 42.1°C | 12.7°C | 3 mm | 39% | 1.7 m/s | 7.2 |
| 2006 | 33.5°C | 25.4°C | 17.4°C | 39.1°C | 13.1°C | 0 mm | 40% | 1.7 m/s | 7.8 |
| 2005 | 33.8°C | 26.3°C | 18.9°C | 40.7°C | 14.3°C | 6 mm | 43% | 1.6 m/s | 7.3 |
| 2004 | 33.2°C | 25.3°C | 17.5°C | 39.8°C | 13.2°C | 7 mm | 42% | 1.7 m/s | 7.5 |
| 2003 | 35.6°C | 27.7°C | 19.7°C | 40.4°C | 15.6°C | 9 mm | 37% | 1.7 m/s | 7.2 |
| 2002 | 33.8°C | 25.2°C | 16.6°C | 40.9°C | 12.9°C | 0 mm | 41% | 1.7 m/s | 7.5 |
| 2001 | 35.0°C | 26.8°C | 18.7°C | 40.3°C | 12.7°C | 1 mm | 37% | 1.7 m/s | 7.6 |
| 2000 | 34.4°C | 26.7°C | 19.1°C | 39.7°C | 13.1°C | 16 mm | 42% | 1.8 m/s | 7.2 |
| 1999 | 34.4°C | 26.0°C | 17.7°C | 40.7°C | 11.5°C | 2 mm | 37% | 1.8 m/s | 7.5 |
| 1998 | 36.0°C | 28.2°C | 20.4°C | 42.3°C | 14.0°C | 11 mm | 41% | 1.6 m/s | 7.2 |
| 1997 | 34.6°C | 26.6°C | 18.5°C | 43.3°C | 12.9°C | 2 mm | 43% | 1.8 m/s | 7.5 |
| 1996 | 36.5°C | 28.0°C | 19.4°C | 41.2°C | 12.7°C | 3 mm | 38% | 1.8 m/s | 7.5 |
| 1995 | 35.6°C | 27.6°C | 19.5°C | 39.7°C | 14.5°C | 2 mm | 36% | 1.8 m/s | 6.7 |
| 1994 | 35.8°C | 27.7°C | 19.5°C | 40.5°C | 13.8°C | 7 mm | 38% | 1.8 m/s | 6.7 |
| 1993 | 32.2°C | 24.4°C | 16.6°C | 39.0°C | 12.3°C | 1 mm | 47% | 1.7 m/s | 7.1 |
| 1992 | 34.8°C | 27.1°C | 19.4°C | 39.8°C | 11.9°C | 7 mm | 43% | 1.7 m/s | 7.1 |
| 1991 | 32.7°C | 24.6°C | 16.4°C | 38.8°C | 10.8°C | 2 mm | 45% | 1.8 m/s | 7.4 |
| 1990 | 33.4°C | 25.2°C | 17.0°C | 38.7°C | 9.8°C | 7 mm | 44% | 1.8 m/s | 6.9 |
| 1989 ❄️ | 32.3°C | 24.0°C | 15.7°C | 36.9°C | 11.8°C | 4 mm | 46% | 1.9 m/s | 7.5 |
| 1988 | 33.4°C | 25.4°C | 17.3°C | 37.5°C | 12.0°C | 12 mm | 44% | 1.7 m/s | 6.7 |
| 1987 | 33.3°C | 25.3°C | 17.3°C | 39.1°C | 11.7°C | 3 mm | 42% | 1.8 m/s | 6.8 |
| 1986 | 36.0°C | 28.0°C | 20.0°C | 38.7°C | 15.4°C | 6 mm | 30% | 1.7 m/s | 7.3 |
| 1985 | 34.7°C | 25.8°C | 16.9°C | 42.4°C | 12.9°C | 0 mm | 33% | 1.8 m/s | 7 |
| 1984 | 34.4°C | 26.7°C | 19.0°C | 39.9°C | 16.1°C | 16 mm | 45% | 1.7 m/s | 6.2 |
| 1983 | 33.3°C | 26.3°C | 19.3°C | 40.1°C | 12.1°C | 48 mm | 47% | 1.6 m/s | — |
| 1982 | 34.6°C | 26.8°C | 19.1°C | 39.3°C | 12.8°C | 7 mm | 33% | 1.6 m/s | — |
| 1981 | 36.2°C | 27.7°C | 19.2°C | 41.7°C | 13.8°C | 2 mm | 29% | 1.8 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 34.6°C with lows near 18.5°C (mean 26.6°C), based on 45 years of NASA POWER data.
August averages 7 mm of rainfall in San Bernardino, one of the drier months. The wettest on record was 73 mm in 2023.
The hottest August reached 43.3°C in 1997. The coldest dipped to 9.8°C in 1990.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 0.6°C. Daytime highs moved from 34.6°C to 35.1°C and overnight lows from 18.7°C to 19.5°C over the same span.
August is one of the warmer months of the year in San Bernardino and one of the drier months, so plan for around 34.6°C daytime highs and 18.5°C at night.
Not quite — August is the 12th coolest month in San Bernardino, averaging 26.6°C.
For August in San Bernardino, pack light, breathable clothing and sun protection, with typical highs of 34.6°C and lows of 18.5°C.
Relative humidity in August averages 39% — relatively dry.
Average wind speed in August is 1.7 m/s. The windiest August on record averaged 1.9 m/s (1989).
The wettest August on record was 2023 with 73 mm. On average, August sees 7 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 San Bernardino 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.
