August is one of the warmer months of the year in Castle Rock, with average highs near 28.3°C and lows around 13.3°C (mean 20.8°C). It is a relatively wet time of year, averaging 59 mm of rainfall and 47% relative humidity across the period.
August is one of the warmer months of the year in Castle Rock. Across 45 years of records, the warmest August in Castle Rock was 2020 — when the month averaged 23.2°C — while the coldest was 2004 at 18.6°C. Typical August days reach 28.3°C with nights near 13.3°C. The long-term trend is warming, about 0.4°C per decade.
August is a relatively wet time of year in Castle Rock, averaging 59 mm of rainfall. The wettest August on record was 1984 with 116 mm, while the driest was 2012 at 18 mm.
Relative humidity in Castle Rock during August averages 47%. The most humid August was 1983 at 57%, and the least humid was 2020 at 36%.
August receives about 6.2 kWh/m²/day of solar energy in Castle Rock. The sunniest August was 2010 at 6.7 kWh/m²/day, and the cloudiest was 1993 at 5.5.
Average wind speed in Castle Rock during August is 2.2 m/s. The windiest Augusts were 2018, 2022 and 2023, among others at 2.4 m/s, while the calmest was 2014 at 1.8 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 20.3°C | 20.2°C | 20.9°C | 21.1°C | 22.2°C | +1.9°C |
| Avg High | 27.6°C | 27.4°C | 28.4°C | 28.7°C | 30.0°C | +2.4°C |
| Avg Low | 13.1°C | 12.9°C | 13.3°C | 13.4°C | 14.4°C | +1.3°C |
| Avg Rain | 63 mm | 67 mm | 66 mm | 45 mm | 49 mm | -13 mm |
August temperatures in Castle Rock have risen by about 1.6°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 4.1°C (1992) to a record high of 36.6°C (2008).
Rainfall in August is a relatively wet time of year, averaging 59 mm, with a wettest year of 116 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.6°C per decade while lows rose 0.3°C per decade, widening the gap between day and night.
One of the best times to visit Castle Rock
August is one of the best times to visit Castle Rock. Expect days averaging 28.3°C and nights around 13.3°C (mean 20.8°C) — warmer than Castle Rock's yearly average — with moderate rainfall (59 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 | 29.9°C | 22.0°C | 14.1°C | 35.6°C | 9.5°C | 58 mm | 44% | 2.2 m/s | 6 |
| 2024 | 30.4°C | 22.6°C | 14.7°C | 35.3°C | 11.3°C | 60 mm | 44% | 2.3 m/s | 6.1 |
| 2023 | 29.2°C | 21.4°C | 13.7°C | 34.4°C | 9.9°C | 65 mm | 48% | 2.4 m/s | 6.5 |
| 2022 | 29.1°C | 21.9°C | 14.7°C | 34.0°C | 10.8°C | 66 mm | 49% | 2.4 m/s | 6.4 |
| 2021 | 30.2°C | 22.0°C | 13.9°C | 33.6°C | 9.7°C | 23 mm | 40% | 2.1 m/s | 6.5 |
| 2020 🔥 | 31.3°C | 23.2°C | 15.0°C | 34.2°C | 7.4°C | 24 mm | 36% | 2.3 m/s | 6.2 |
| 2019 | 30.5°C | 22.5°C | 14.4°C | 33.7°C | 10.7°C | 33 mm | 43% | 2.2 m/s | 6.5 |
| 2018 | 28.7°C | 20.9°C | 13.1°C | 32.9°C | 8.5°C | 31 mm | 45% | 2.4 m/s | 6.2 |
| 2017 | 27.5°C | 20.1°C | 12.6°C | 31.9°C | 10.8°C | 60 mm | 50% | 2.1 m/s | 6.2 |
| 2016 | 27.1°C | 19.7°C | 12.3°C | 33.0°C | 5.8°C | 39 mm | 49% | 2.3 m/s | 6.1 |
| 2015 | 28.8°C | 21.2°C | 13.5°C | 33.1°C | 5.7°C | 44 mm | 48% | 2.2 m/s | 6.4 |
| 2014 | 26.7°C | 19.4°C | 12.0°C | 31.2°C | 8.5°C | 60 mm | 53% | 1.8 m/s | 6.2 |
| 2013 | 28.4°C | 21.1°C | 13.8°C | 33.4°C | 10.3°C | 76 mm | 49% | 2.1 m/s | 6.3 |
| 2012 | 29.8°C | 21.9°C | 14.0°C | 33.8°C | 9.1°C | 18 mm | 39% | 2.4 m/s | 6.3 |
| 2011 | 30.7°C | 22.9°C | 15.0°C | 33.4°C | 10.5°C | 41 mm | 42% | 2.1 m/s | 6.6 |
| 2010 | 29.0°C | 21.2°C | 13.3°C | 32.9°C | 9.6°C | 49 mm | 46% | 2.3 m/s | 6.7 |
| 2009 | 28.3°C | 20.1°C | 11.9°C | 33.5°C | 7.7°C | 29 mm | 45% | 2.1 m/s | 6.4 |
| 2008 | 28.3°C | 20.7°C | 13.1°C | 36.6°C | 6.7°C | 102 mm | 48% | 2.3 m/s | 6.2 |
| 2007 | 29.8°C | 22.2°C | 14.7°C | 33.9°C | 11.5°C | 83 mm | 49% | 2.1 m/s | 6.4 |
| 2006 | 27.0°C | 20.2°C | 13.3°C | 32.1°C | 7.6°C | 72 mm | 52% | 2.4 m/s | 6.1 |
| 2005 | 27.5°C | 20.1°C | 12.6°C | 34.5°C | 7.7°C | 69 mm | 47% | 2.1 m/s | 6.2 |
| 2004 ❄️ | 26.2°C | 18.6°C | 11.1°C | 33.3°C | 5.2°C | 70 mm | 51% | 2.2 m/s | 6.4 |
| 2003 | 29.3°C | 22.1°C | 14.9°C | 34.1°C | 8.5°C | 61 mm | 45% | 2.3 m/s | 6.3 |
| 2002 | 29.9°C | 21.5°C | 13.0°C | 36.2°C | 7.2°C | 33 mm | 37% | 2.3 m/s | 6.5 |
| 2001 | 28.2°C | 21.0°C | 13.9°C | 33.2°C | 10.2°C | 54 mm | 46% | 2.3 m/s | 6 |
| 2000 | 29.6°C | 22.1°C | 14.6°C | 33.7°C | 11.1°C | 84 mm | 45% | 2.2 m/s | 6.2 |
| 1999 | 27.0°C | 19.9°C | 12.9°C | 30.8°C | 9.8°C | 78 mm | 54% | 2.1 m/s | 6.3 |
| 1998 | 27.5°C | 20.3°C | 13.1°C | 31.7°C | 9.9°C | 55 mm | 51% | 2.1 m/s | 6.3 |
| 1997 | 27.0°C | 19.8°C | 12.6°C | 31.2°C | 7.8°C | 106 mm | 55% | 2.1 m/s | 6.1 |
| 1996 | 28.0°C | 20.4°C | 12.8°C | 33.1°C | 10.1°C | 44 mm | 46% | 2.3 m/s | 6.3 |
| 1995 | 29.7°C | 22.2°C | 14.6°C | 34.6°C | 9.4°C | 46 mm | 45% | 2.1 m/s | 6.6 |
| 1994 | 28.7°C | 21.4°C | 14.0°C | 33.5°C | 9.6°C | 65 mm | 47% | 2.2 m/s | 5.7 |
| 1993 | 26.0°C | 19.1°C | 12.2°C | 31.2°C | 5.3°C | 52 mm | 50% | 2.2 m/s | 5.5 |
| 1992 | 26.0°C | 18.8°C | 11.6°C | 31.4°C | 4.1°C | 91 mm | 51% | 2.1 m/s | 5.8 |
| 1991 | 26.8°C | 19.8°C | 12.9°C | 30.4°C | 8.7°C | 76 mm | 53% | 2.2 m/s | 6.2 |
| 1990 | 27.4°C | 19.8°C | 12.2°C | 34.7°C | 9.6°C | 54 mm | 46% | 2.2 m/s | 6.3 |
| 1989 | 27.8°C | 20.0°C | 12.3°C | 31.7°C | 9.9°C | 39 mm | 44% | 2.3 m/s | 6.4 |
| 1988 | 28.7°C | 21.2°C | 13.7°C | 34.8°C | 9.0°C | 62 mm | 46% | 2.2 m/s | 6.2 |
| 1987 | 26.8°C | 19.5°C | 12.2°C | 32.6°C | 8.0°C | 71 mm | 50% | 2.1 m/s | 6 |
| 1986 | 27.5°C | 20.1°C | 12.8°C | 33.4°C | 8.6°C | 49 mm | 47% | 2.3 m/s | 6.1 |
| 1985 | 29.6°C | 21.1°C | 12.5°C | 33.8°C | 8.1°C | 28 mm | 37% | 2.2 m/s | 6.4 |
| 1984 🌧️ | 26.7°C | 20.0°C | 13.3°C | 30.3°C | 10.1°C | 116 mm | 57% | 2.1 m/s | 5.8 |
| 1983 | 27.0°C | 20.7°C | 14.4°C | 32.0°C | 11.5°C | 71 mm | 57% | 1.9 m/s | — |
| 1982 | 27.8°C | 21.0°C | 14.2°C | 32.5°C | 11.5°C | 72 mm | 53% | 2.1 m/s | — |
| 1981 | 26.5°C | 19.3°C | 12.1°C | 32.7°C | 9.0°C | 56 mm | 52% | 2 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 28.3°C with lows near 13.3°C (mean 20.8°C), based on 45 years of NASA POWER data.
August averages 59 mm of rainfall in Castle Rock, a relatively wet time of year. The wettest on record was 116 mm in 1984.
The hottest August reached 36.6°C in 2008. The coldest dipped to 4.1°C in 1992.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 1.6°C. Daytime highs moved from 27.5°C to 29.8°C and overnight lows from 13.3°C to 14.2°C over the same span.
August is one of the warmer months of the year in Castle Rock and a relatively wet time of year, so plan for around 28.3°C daytime highs and 13.3°C at night.
Not quite — August is the 11th coolest month in Castle Rock, averaging 20.8°C.
For August in Castle Rock, pack light layers you can adjust through the day, with typical highs of 28.3°C and lows of 13.3°C. Bring an umbrella or light rain jacket too.
Relative humidity in August averages 47% — relatively dry.
Average wind speed in August is 2.2 m/s. The windiest August on record averaged 2.4 m/s (2006).
The wettest August on record was 1984 with 116 mm. On average, August sees 59 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 Castle Rock 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.
