Climate averages 1991–2020
Cardiff weather
in August.
A mild, moderately wet month: the 2nd warmest and the 8th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
August is a mild month in Cardiff: daytime highs average 19.2°C and nights cool to about 13.5°C. By daytime temperature it is the 2nd warmest of the 12 months.
Expect about 87 mm of rain on roughly 12 days, which makes August a moderately wet month (the 8th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 14 h 37 min on an average August day.
The nearest other city in this atlas is Newport (17 km away). In August its highs average 20.1°C, 0.8°C warmer than Cardiff, with 74 mm of rain.
Among the 143 cities listed in the United Kingdom, Cardiff ranks joint 97th of 143 for the warmest August highs and 120th of 143 for the driest August (rainfall, lowest first). The mean August high of those 143 cities is 19.7°C; Cardiff is 0.5°C cooler than that mean.
From August to September, average highs fall by 2.0°C to 17.2°C, and monthly rainfall falls from 87 mm to 74 mm.
The annual picture
August in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Cardiff climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 7.4°C3.3°C | 3.3°C | 95 | 14.5 | 8.48 h |
| February | 7.8°C3.0°C | 3.0°C | 75 | 11.3 | 9.910 h |
| March | 9.6°C3.9°C | 3.9°C | 68 | 11.7 | 11.812 h |
| April | 12.2°C5.5°C | 5.5°C | 70 | 11.6 | 13.814 h |
| May | 15.2°C8.5°C | 8.5°C | 73 | 12.3 | 15.616 h |
| June | 17.7°C11.4°C | 11.4°C | 71 | 11.0 | 16.517 h |
| July | 19.4°C13.4°C | 13.4°C | 74 | 11.6 | 16.116 h |
| August, selected | 19.2°C13.5°C | 13.5°C | 87 | 12.3 | 14.615 h |
| September | 17.2°C11.5°C | 11.5°C | 74 | 11.0 | 12.713 h |
| October | 13.8°C9.0°C | 9.0°C | 106 | 14.0 | 10.711 h |
| November | 10.3°C6.1°C | 6.1°C | 102 | 14.5 | 8.99 h |
| December | 7.9°C3.9°C | 3.9°C | 107 | 13.7 | 7.98 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
August in nearby cities
- Newport in AugustUnited Kingdom · 17 kmHigh 20.1°C · Low 13.0°C · 74 mm rain
- Weston-super-Mare in AugustUnited Kingdom · 21 kmHigh 19.8°C · Low 13.6°C · 73 mm rain
- Bristol in AugustUnited Kingdom · 41 kmHigh 20.1°C · Low 13.1°C · 69 mm rain
- Swansea in AugustUnited Kingdom · 55 kmHigh 18.5°C · Low 13.8°C · 101 mm rain
- Bath in AugustUnited Kingdom · 58 kmHigh 19.8°C · Low 12.6°C · 67 mm rain
- Gloucester, United Kingdom in AugustUnited Kingdom · 78 kmHigh 20.5°C · Low 12.9°C · 63 mm rain
- Exeter in AugustUnited Kingdom · 88 kmHigh 19.7°C · Low 13.3°C · 65 mm rain
- Cheltenham in AugustUnited Kingdom · 89 kmHigh 20.3°C · Low 12.8°C · 62 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Cardiff) is explained once on the Cardiff year overview and on the Sources, method and limits page.