August is one of the warmer months of the year in Cardiff, with average highs near 19.9°C and lows around 12.7°C (mean 16.3°C). It is about average for rainfall, averaging 76 mm of rainfall and 83% relative humidity across the period.
August is one of the warmer months of the year in Cardiff. Across 45 years of records, the warmest August in Cardiff was 1995 — when the month averaged 19°C — while the coldest was 1986 at 13.8°C. Typical August days reach 19.9°C with nights near 12.7°C. The long-term trend is warming, about 0.2°C per decade.
August is about average for rainfall in Cardiff, averaging 76 mm of rainfall. The wettest August on record was 1999 with 159 mm, while the driest was 1995 at 9 mm.
Relative humidity in Cardiff during August averages 83%. The most humid August was 2008 at 87%, and the least humid was 1995 at 74%.
August receives about 4.3 kWh/m²/day of solar energy in Cardiff. The sunniest August was 1995 at 5.4 kWh/m²/day, and the cloudiest was 2008 at 3.4.
Average wind speed in Cardiff during August is 3.4 m/s. The windiest August was 1985 at 4.7 m/s, while the calmest was 1981 at 2.5 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 15.8°C | 16.5°C | 16.4°C | 16.0°C | 17.2°C | +1.4°C |
| Avg High | 19.4°C | 20.3°C | 19.9°C | 19.3°C | 20.9°C | +1.5°C |
| Avg Low | 12.2°C | 12.8°C | 12.9°C | 12.6°C | 13.5°C | +1.3°C |
| Avg Rain | 67 mm | 79 mm | 70 mm | 95 mm | 62 mm | -5 mm |
August temperatures in Cardiff have risen by about 0.8°C between 1981–1985 and 2021–2025.
August has ranged from a record low of 7.3°C (1986) to a record high of 30.3°C (2022).
Rainfall in August is about average for rainfall, averaging 76 mm, with a wettest year of 159 mm.
One of the best times to visit Cardiff
August is one of the best times to visit Cardiff. Expect days averaging 19.9°C and nights around 12.7°C (mean 16.3°C) — warmer than Cardiff's yearly average — with moderate rainfall (76 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 | 21.8°C | 17.7°C | 13.7°C | 30.3°C | 10.7°C | 42 mm | 79% | 3.4 m/s | 4.6 |
| 2024 | 20.2°C | 16.8°C | 13.3°C | 26.2°C | 10.9°C | 61 mm | 84% | 3.8 m/s | 4 |
| 2023 | 20.0°C | 16.5°C | 12.9°C | 23.7°C | 10.8°C | 75 mm | 85% | 3.6 m/s | 3.9 |
| 2022 | 23.1°C | 18.6°C | 14.1°C | 30.3°C | 9.8°C | 25 mm | 76% | 2.9 m/s | 5 |
| 2021 | 19.6°C | 16.1°C | 12.6°C | 21.4°C | 9.6°C | 54 mm | 85% | 3.4 m/s | 4 |
| 2020 | 20.8°C | 17.5°C | 14.1°C | 29.2°C | 8.7°C | 114 mm | 83% | 3.7 m/s | 3.9 |
| 2019 | 20.2°C | 16.8°C | 13.4°C | 25.1°C | 10.7°C | 95 mm | 84% | 3.9 m/s | 4.5 |
| 2018 | 20.3°C | 16.8°C | 13.3°C | 25.1°C | 8.4°C | 93 mm | 82% | 3.4 m/s | 4.1 |
| 2017 | 18.8°C | 15.6°C | 12.5°C | 22.7°C | 9.6°C | 71 mm | 84% | 3.5 m/s | 4.3 |
| 2016 | 20.1°C | 16.6°C | 13.1°C | 24.5°C | 9.7°C | 85 mm | 85% | 3.7 m/s | 4.4 |
| 2015 | 18.9°C | 15.5°C | 12.1°C | 23.6°C | 10.2°C | 140 mm | 84% | 3.5 m/s | 3.7 |
| 2014 | 18.1°C | 14.9°C | 11.8°C | 20.8°C | 8.3°C | 114 mm | 82% | 4 m/s | 4.3 |
| 2013 | 20.3°C | 16.6°C | 13.0°C | 25.9°C | 10.0°C | 71 mm | 83% | 3.4 m/s | 4.3 |
| 2012 | 19.3°C | 16.2°C | 13.2°C | 23.0°C | 7.9°C | 105 mm | 86% | 3.6 m/s | 3.9 |
| 2011 | 18.3°C | 15.2°C | 12.1°C | 22.2°C | 9.5°C | 75 mm | 83% | 3.3 m/s | 4 |
| 2010 | 19.1°C | 15.6°C | 12.0°C | 22.5°C | 7.6°C | 96 mm | 83% | 3.8 m/s | 4 |
| 2009 | 19.4°C | 16.2°C | 12.9°C | 22.4°C | 10.4°C | 57 mm | 85% | 3.8 m/s | 4 |
| 2008 | 18.9°C | 16.0°C | 13.2°C | 22.6°C | 9.6°C | 125 mm | 87% | 4.2 m/s | 3.4 |
| 2007 | 19.2°C | 15.5°C | 11.8°C | 23.1°C | 9.0°C | 60 mm | 84% | 3.5 m/s | 4.7 |
| 2006 | 19.3°C | 16.1°C | 12.9°C | 23.8°C | 10.2°C | 53 mm | 82% | 3.8 m/s | 4.2 |
| 2005 | 20.1°C | 16.2°C | 12.3°C | 24.1°C | 9.0°C | 51 mm | 82% | 3.1 m/s | 4.9 |
| 2004 | 20.4°C | 17.0°C | 13.6°C | 25.2°C | 9.6°C | 115 mm | 84% | 3.3 m/s | 4.3 |
| 2003 | 22.2°C | 17.9°C | 13.7°C | 28.8°C | 8.7°C | 25 mm | 80% | 2.6 m/s | 4.6 |
| 2002 | 20.0°C | 16.3°C | 12.6°C | 22.0°C | 10.6°C | 43 mm | 84% | 2.6 m/s | 4.1 |
| 2001 | 19.8°C | 16.3°C | 12.9°C | 23.6°C | 9.6°C | 96 mm | 85% | 3.2 m/s | 3.9 |
| 2000 | 19.9°C | 16.5°C | 13.1°C | 24.8°C | 10.5°C | 78 mm | 84% | 3.2 m/s | 4.3 |
| 1999 🌧️ | 19.6°C | 16.3°C | 13.1°C | 24.2°C | 9.4°C | 159 mm | 85% | 2.8 m/s | 4.1 |
| 1998 | 19.5°C | 15.6°C | 11.6°C | 25.3°C | 9.0°C | 48 mm | 84% | 3.4 m/s | 4.8 |
| 1997 | 21.8°C | 18.3°C | 14.9°C | 26.3°C | 12.6°C | 152 mm | 84% | 2.9 m/s | 4 |
| 1996 | 19.8°C | 15.9°C | 12.0°C | 25.0°C | 8.9°C | 72 mm | 82% | 3.4 m/s | 4.5 |
| 1995 🔥 | 23.8°C | 19.0°C | 14.3°C | 29.6°C | 10.0°C | 9 mm | 74% | 2.9 m/s | 5.4 |
| 1994 | 19.3°C | 15.9°C | 12.4°C | 22.9°C | 8.3°C | 77 mm | 82% | 3.6 m/s | 4.4 |
| 1993 | 18.4°C | 14.7°C | 11.0°C | 21.0°C | 8.0°C | 47 mm | 82% | 3.3 m/s | 4.4 |
| 1992 | 18.5°C | 15.3°C | 12.2°C | 21.9°C | 9.0°C | 152 mm | 82% | 4.1 m/s | 4 |
| 1991 | 20.6°C | 16.5°C | 12.4°C | 24.5°C | 8.9°C | 25 mm | 82% | 3.1 m/s | 4.7 |
| 1990 | 21.5°C | 17.5°C | 13.6°C | 30.0°C | 11.0°C | 47 mm | 80% | 3.3 m/s | 4.5 |
| 1989 | 20.1°C | 16.4°C | 12.6°C | 23.2°C | 9.2°C | 45 mm | 80% | 3.8 m/s | 4.7 |
| 1988 | 18.4°C | 14.9°C | 11.5°C | 25.2°C | 8.4°C | 76 mm | 83% | 3.7 m/s | 4.1 |
| 1987 | 19.5°C | 15.9°C | 12.2°C | 24.9°C | 8.1°C | 32 mm | 82% | 3.1 m/s | 4.1 |
| 1986 ❄️ | 17.1°C | 13.8°C | 10.5°C | 21.0°C | 7.3°C | 115 mm | 82% | 3.6 m/s | 3.5 |
| 1985 | 17.3°C | 14.5°C | 11.7°C | 22.0°C | 8.9°C | 132 mm | 85% | 4.7 m/s | 3.9 |
| 1984 | 21.5°C | 17.6°C | 13.7°C | 26.5°C | 9.7°C | 51 mm | 79% | 2.7 m/s | 4.6 |
| 1983 | 21.4°C | 17.1°C | 12.8°C | 26.7°C | 8.9°C | 29 mm | 81% | 2.8 m/s | — |
| 1982 | 18.9°C | 15.7°C | 12.5°C | 24.7°C | 9.5°C | 74 mm | 83% | 3.9 m/s | — |
| 1981 | 20.5°C | 16.5°C | 12.5°C | 24.1°C | 8.5°C | 49 mm | 83% | 2.5 m/s | — |
Actual recorded August data for each year, 1981–2025 — sourced from NASA POWER.
The average high in August is around 19.9°C with lows near 12.7°C (mean 16.3°C), based on 45 years of NASA POWER data.
August averages 76 mm of rainfall in Cardiff, about average for rainfall. The wettest on record was 159 mm in 1999.
The hottest August reached 30.3°C in 2022. The coldest dipped to 7.3°C in 1986.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average August temperatures have risen by about 0.8°C. Daytime highs moved from 19.9°C to 20.9°C and overnight lows from 12.6°C to 13.3°C over the same span.
August is one of the warmer months of the year in Cardiff and about average for rainfall, so plan for around 19.9°C daytime highs and 12.7°C at night.
Not quite — August is the 11th coolest month in Cardiff, averaging 16.3°C.
For August in Cardiff, pack light layers you can adjust through the day, with typical highs of 19.9°C and lows of 12.7°C. Bring an umbrella or light rain jacket too.
Relative humidity in August averages 83% — quite humid.
Average wind speed in August is 3.4 m/s. The windiest August on record averaged 4.7 m/s (1985).
The wettest August on record was 1999 with 159 mm. On average, August sees 76 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 Cardiff 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.
