Cardiff weather in August
In August, Cardiff has daytime highs averaging 19 °C, nights around 13 °C, with 13 wet days, and a sea temperature of 18 °C. Figures are 1991–2020 climate normals.
- 19.3°C Average high
- 13.3°C Average low
- 13days Wet days
- 89mm Rainfall
- 18.2°C Sea temperature
- 15h Daylight
Daily temperatures through August
How August develops
Averages for the first, middle and last part of the month, from daily 1991–2020 normals. Chance of rain is the share of years in which that calendar day recorded more than 1 mm.
| Days | Avg high | Avg low | Chance of rain |
|---|---|---|---|
| 1–10 August | 19.9 °C | 13.8 °C | 42 % |
| 11–20 August | 19.4 °C | 13.5 °C | 39 % |
| 21–31 August | 18.7 °C | 12.9 °C | 40 % |
- Average highs fall from 19.9 °C early in August to 18.7 °C by the end of it.
What to expect
| Measure | Typical August | Share of the month |
|---|---|---|
| Days above 25 °C | 1.1 of 31 | 4 % |
| Days above 30 °C | 0.07 of 31 | 0 % |
| Days below 0 °C | 0 of 31 | 0 % |
| Days with more than 1 mm rain | 13 of 31 | 40 % |
Conditions in August
| Measure | Average |
|---|---|
| Mean temperature | 16 °C |
| Record high (1991–2020) | 31 °C |
| Record low (1991–2020) | 7.5 °C |
| Relative humidity | 79 % |
| Wind speed | 21 km/h |
| Cloud cover | 67 % |
Where Cardiff ranks in August
| Ranking | Position | Value |
|---|---|---|
| The coolest places in Europe in August | 44thof 50 | 19 °C |
August compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| June | 17.8 °C | 71 mm | 66 % |
| July | 19.5 °C | 75 mm | 65 % |
| August | 19.3 °C | 89 mm | 67 % |
| September | 17.2 °C | 77 mm | 67 % |
| October | 13.8 °C | 108 mm | 71 % |
See all twelve months for Cardiff
- August is the 2nd warmest month here.
- It is the 8th driest month of the year.
- It ranks 5th for least cloud cover.
- Days last about 15 hours from sunrise to sunset.
- It rains on 13 of 31 days — 40 % of the month.
- Nights are about 5.9 °C cooler than the middle of the day.
- The hottest August day on record since 1991 reached 31 °C, 12 °C above the usual daytime high.
- Beach score: 39 / 100 — see how this is calculated.
Nearby destinations in August
| Destination | Avg high | Wet days | Sea |
|---|---|---|---|
| Cardiff | 19 °C | 13 | 18 |
| Newport | 20 °C | 11 | 18 |
| Bristol | 20 °C | 11 | 18 |
| Swansea | 19 °C | 15 | 18 |
| Swindon | 20 °C | 11 | – |
QuestionsAugust in Cardiff, answered
How warm is Cardiff in August?
Daily highs average 19 °C and nights fall to about 13 °C, a spread of 5.9 °C between afternoon and dawn. That makes August the 2nd warmest month of the year here.
Does it rain much in Cardiff in August?
August averages 89 mm of rain, spread over about 13 of the 31 days — 40 % of the month. Cloud cover averages 67 % of the sky.
Is the sea warm enough to swim in August?
The sea averages 18 °C off Cardiff in August. Most people find water below 20 °C bracing and above 25 °C comfortable for a long swim; this figure is a monthly surface average, so a sheltered bay on a still afternoon can be warmer.
How long are the days in August?
Cardiff averages 15 hours between sunrise and sunset in August. Day length is computed from latitude and date, so it is exact rather than modelled — but it says nothing about how much of that time is sunny.
Data sources and method
- ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
- Open-Meteo — Open-Meteo.com. CC BY 4.0
- NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
- GeoNames — GeoNames.org. CC BY 4.0
- Normal period
- 1991–2020
- Dataset version
- era5-1991-2020-scores1.1
- Last processed
Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: daylight hours, beach and comfort scores, monthly rankings, threshold day counts, chance of a wet day by date, ten-day averages within the month. Full formulas are on the methodology page.
Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.