Cardiff weather in August
Temperature, sea and sunshine in August: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in August
Good
Best time to visit: June – September
What is the weather like in Cardiff in August?
In August, Cardiff is mild: daytime highs average 19 °C, and nights cool down to about 14 °C. The sea averages 18.4 °C – bracing, so a wetsuit helps for longer swims. Expect around 6 hours of sunshine a day. Rain is frequent, with about 12 rainy days and 72 mm in total. All in all, August is a good month for a holiday in Cardiff.
August compared
How the weather changes from July to September. Tap a month to open it.
| JulyJul | AugustAug | SeptemberSep | |
|---|---|---|---|
| Score | 77 | 74 | 71 |
| Day | 20° | 19° | 18° |
| Night | 14° | 14° | 12° |
| Sea | 18° | 18° | 17° |
| Sun | 7 h | 6 h | 5 h |
| Rain days | 11 | 12 | 10 |
More details for August
- Daylight
- 14 h 41 min05:57 – 20:38
- UV index
- 6 · highclear sky, noon (estimate)All months
- Muggy days
- 0 daysdew point 18 °C or moreAll months
- Wind
- 21 km/haverage daily peakAll months
- Cloud cover
- 66 %on averageAll months
- Hot days
- 0 days30 °C or more
- Time zone
- UTC+1Europe/London
How the score comes together
- Temperatureweight 50 %100 %
- Sunshineweight 20 %50 %
- Few rainy daysweight 30 %46 %
Each factor is rated from 0 to 100 % and weighted for the travel style “City break”.
What to pack in August
- Wetsuit for longer swims
- Sunscreen
- A jumper for the evenings
- Rain jacket or umbrella
Cardiff in August: quick answers
Is Cardiff hot in August?
No. In August, Cardiff is mild: daytime highs average 19 °C and nights drop to about 14 °C.
Can you swim in Cardiff in August?
Only if you don't mind cold water: in August the sea averages just 18.4 °C. Comfortable swimming temperatures are not reached at any time of year.
Does it rain much in Cardiff in August?
Rain is frequent, with about 12 rainy days and 72 mm in total.
Cardiff month by month
The whole year in CardiffAll destinations: United KingdomWhere to go in AugustSea temperature in August
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences