August is one of the warmer months of the year in Saint Helens, with average highs near 18.8°C and lows around 11.3°C (mean 15.1°C). It is about average for rainfall, averaging 85 mm of rainfall and 85% relative humidity across the period.
August is one of the warmer months of the year in Saint Helens. Across 45 years of records, the warmest Augusts in Saint Helens were 1997 and 2022 — when the month averaged 17°C — while the coldest was 1986 at 12.2°C. Typical August days reach 18.8°C with nights near 11.3°C. The long-term trend is warming, about 0.2°C per decade.
August is about average for rainfall in Saint Helens, averaging 85 mm of rainfall. The wettest August on record was 2004 with 184 mm, while the driest was 1995 at 19 mm.
Relative humidity in Saint Helens during August averages 85%. The most humid August was 2002 at 87%, and the least humid was 2022 at 80%.
August receives about 4.1 kWh/m²/day of solar energy in Saint Helens. The sunniest August was 1995 at 5 kWh/m²/day, and the cloudiest was 2008 at 3.4.
Average wind speed in Saint Helens during August is 3.1 m/s. The windiest August was 1985 at 4.3 m/s, while the calmest were 1983 and 1984 at 2.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 14.4°C | 15.1°C | 15.3°C | 14.8°C | 16.0°C | +1.6°C |
| Avg High | 18.1°C | 19.0°C | 19.0°C | 18.5°C | 19.8°C | +1.7°C |
| Avg Low | 10.7°C | 11.1°C | 11.7°C | 11.1°C | 12.1°C | +1.4°C |
| Avg Rain | 87 mm | 75 mm | 96 mm | 94 mm | 68 mm | -19 mm |
August temperatures in Saint Helens have risen by about 0.9°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 5.4°C (2020) to a record high of 28.3°C (1990).
Rainfall in August is about average for rainfall, averaging 85 mm, with a wettest year of 184 mm.
One of the best times to visit Saint Helens
August is one of the best times to visit Saint Helens. Expect days averaging 18.8°C and nights around 11.3°C (mean 15.1°C) — warmer than Saint Helens's yearly average — with higher rainfall (85 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 | 20.4°C | 16.3°C | 12.2°C | 25.7°C | 9.5°C | 33 mm | 82% | 3 m/s | 4.3 |
| 2024 | 19.3°C | 15.6°C | 11.9°C | 23.8°C | 8.2°C | 53 mm | 84% | 3.5 m/s | 4 |
| 2023 | 19.1°C | 15.5°C | 11.8°C | 24.7°C | 9.5°C | 105 mm | 85% | 3.2 m/s | 4.2 |
| 2022 | 21.4°C | 17.0°C | 12.6°C | 27.9°C | 8.9°C | 38 mm | 80% | 2.4 m/s | 4.7 |
| 2021 | 18.8°C | 15.2°C | 11.5°C | 21.6°C | 8.7°C | 59 mm | 85% | 2.7 m/s | 3.9 |
| 2020 | 20.0°C | 16.2°C | 12.4°C | 27.4°C | 5.4°C | 120 mm | 85% | 3.4 m/s | 3.9 |
| 2019 | 19.6°C | 15.9°C | 12.1°C | 26.3°C | 9.3°C | 114 mm | 85% | 3.4 m/s | 4.1 |
| 2018 | 19.2°C | 15.5°C | 11.7°C | 24.0°C | 6.6°C | 64 mm | 85% | 2.9 m/s | 3.8 |
| 2017 | 17.8°C | 14.2°C | 10.6°C | 21.9°C | 7.8°C | 87 mm | 86% | 3 m/s | 4.2 |
| 2016 | 19.0°C | 15.4°C | 11.8°C | 23.5°C | 8.9°C | 96 mm | 86% | 3.4 m/s | 4.1 |
| 2015 | 18.8°C | 14.7°C | 10.7°C | 22.8°C | 7.3°C | 98 mm | 83% | 3 m/s | 4.1 |
| 2014 | 17.0°C | 13.7°C | 10.4°C | 20.4°C | 6.1°C | 118 mm | 84% | 3.7 m/s | 4.2 |
| 2013 | 19.2°C | 15.4°C | 11.5°C | 25.7°C | 9.0°C | 87 mm | 85% | 3 m/s | 4.2 |
| 2012 | 18.8°C | 15.1°C | 11.5°C | 22.4°C | 6.6°C | 113 mm | 87% | 2.9 m/s | 3.8 |
| 2011 | 17.6°C | 14.1°C | 10.6°C | 22.2°C | 8.3°C | 87 mm | 84% | 2.8 m/s | 3.7 |
| 2010 | 17.7°C | 13.9°C | 10.1°C | 22.7°C | 5.8°C | 73 mm | 85% | 3.2 m/s | 4.2 |
| 2009 | 18.9°C | 15.3°C | 11.7°C | 22.7°C | 8.8°C | 87 mm | 85% | 3.5 m/s | 4 |
| 2008 | 18.6°C | 15.3°C | 12.0°C | 22.6°C | 7.6°C | 127 mm | 87% | 3.3 m/s | 3.4 |
| 2007 | 18.1°C | 14.4°C | 10.7°C | 23.3°C | 7.9°C | 65 mm | 86% | 3.1 m/s | 4.2 |
| 2006 | 17.9°C | 14.7°C | 11.5°C | 23.2°C | 9.0°C | 96 mm | 86% | 3.4 m/s | 3.9 |
| 2005 | 18.9°C | 14.9°C | 11.0°C | 24.3°C | 8.3°C | 70 mm | 85% | 3 m/s | 4.5 |
| 2004 🌧️ | 19.8°C | 16.3°C | 12.8°C | 24.7°C | 8.5°C | 184 mm | 86% | 2.9 m/s | 4 |
| 2003 | 20.3°C | 16.3°C | 12.3°C | 27.5°C | 6.9°C | 31 mm | 84% | 2.4 m/s | 4.3 |
| 2002 | 19.3°C | 15.4°C | 11.6°C | 24.3°C | 9.2°C | 115 mm | 87% | 2.4 m/s | 3.8 |
| 2001 | 19.1°C | 15.4°C | 11.6°C | 23.0°C | 8.6°C | 100 mm | 85% | 2.6 m/s | 3.9 |
| 2000 | 18.8°C | 15.0°C | 11.3°C | 22.9°C | 8.2°C | 89 mm | 86% | 2.6 m/s | 4.2 |
| 1999 | 18.3°C | 14.7°C | 11.0°C | 24.8°C | 5.5°C | 112 mm | 86% | 2.9 m/s | 3.8 |
| 1998 | 18.3°C | 14.6°C | 10.9°C | 23.1°C | 6.5°C | 68 mm | 86% | 3.4 m/s | 4.2 |
| 1997 🔥 | 21.2°C | 17.0°C | 12.7°C | 25.6°C | 9.2°C | 79 mm | 85% | 2.7 m/s | 4.3 |
| 1996 | 18.8°C | 15.0°C | 11.2°C | 24.8°C | 8.2°C | 87 mm | 84% | 2.8 m/s | 4.2 |
| 1995 | 21.4°C | 16.8°C | 12.1°C | 26.7°C | 7.2°C | 19 mm | 81% | 2.7 m/s | 5 |
| 1994 | 17.8°C | 14.3°C | 10.7°C | 23.4°C | 7.1°C | 86 mm | 83% | 3.2 m/s | 4.2 |
| 1993 | 17.0°C | 13.0°C | 9.0°C | 20.4°C | 5.5°C | 63 mm | 85% | 2.8 m/s | 4.2 |
| 1992 | 17.3°C | 13.7°C | 10.2°C | 20.4°C | 6.2°C | 130 mm | 83% | 3.7 m/s | 4.1 |
| 1991 | 19.8°C | 15.4°C | 11.0°C | 22.4°C | 7.9°C | 42 mm | 84% | 2.8 m/s | 4.1 |
| 1990 | 20.0°C | 16.2°C | 12.3°C | 28.3°C | 8.3°C | 64 mm | 83% | 3.2 m/s | 3.9 |
| 1989 | 18.5°C | 14.7°C | 10.8°C | 22.0°C | 6.6°C | 78 mm | 83% | 3.4 m/s | 4.2 |
| 1988 | 17.3°C | 13.8°C | 10.3°C | 24.3°C | 8.3°C | 90 mm | 84% | 3.5 m/s | 4.2 |
| 1987 | 17.5°C | 14.2°C | 10.9°C | 23.9°C | 6.9°C | 109 mm | 86% | 3 m/s | 3.8 |
| 1986 ❄️ | 15.6°C | 12.2°C | 8.7°C | 18.6°C | 6.2°C | 109 mm | 84% | 3.5 m/s | 3.8 |
| 1985 | 16.5°C | 13.3°C | 10.1°C | 19.8°C | 7.4°C | 117 mm | 86% | 4.3 m/s | 3.6 |
| 1984 | 20.6°C | 16.3°C | 12.0°C | 24.7°C | 7.9°C | 56 mm | 82% | 2.3 m/s | 4.5 |
| 1983 | 20.0°C | 15.6°C | 11.1°C | 24.3°C | 6.0°C | 47 mm | 83% | 2.3 m/s | — |
| 1982 | 18.0°C | 14.5°C | 11.0°C | 25.0°C | 7.4°C | 107 mm | 84% | 3.6 m/s | — |
| 1981 | 18.9°C | 15.1°C | 11.2°C | 22.1°C | 7.9°C | 71 mm | 85% | 2.5 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 18.8°C with lows near 11.3°C (mean 15.1°C), based on 45 years of NASA POWER data.
August averages 85 mm of rainfall in Saint Helens, about average for rainfall. The wettest on record was 184 mm in 2004.
The hottest August reached 28.3°C in 1990. The coldest dipped to 5.4°C in 2020.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 0.9°C. Daytime highs moved from 18.8°C to 19.8°C and overnight lows from 11.1°C to 12°C over the same span.
August is one of the warmer months of the year in Saint Helens and about average for rainfall, so plan for around 18.8°C daytime highs and 11.3°C at night.
Not quite — August is the 11th coolest month in Saint Helens, averaging 15.1°C.
For August in Saint Helens, pack light layers you can adjust through the day, with typical highs of 18.8°C and lows of 11.3°C. Bring an umbrella or light rain jacket too.
Relative humidity in August averages 85% — quite humid.
Average wind speed in August is 3.1 m/s. The windiest August on record averaged 4.3 m/s (1985).
The wettest August on record was 2004 with 184 mm. On average, August sees 85 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 Saint Helens 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.
