September · United Kingdom
Best time to visit Cardiff in September Weather, crowds & prices
Weather in Cardiff in September
Average temperature 15°C, 96 mm of rain, about 6 days with 6+ hours of sunshine and 85% humidity — based on the five most recent complete years of ERA5 data (2021–2025).
September score
6.7/10
Ranked #6 of 12 months
- Avg temp
- 15°C
- Rainfall
- 96 mm
- Humidity
- 85%
- Days with 6h+ sun
- 6
- Crowd Density
- Moderate Crowds
- Average Expenses
- $$ · Moderate Cost ($$)
September in Cardiff scores 6.7/10 for sightseeing and cultural travel - an above-average month (#6 of 12). Expect around 15°C, 96 mm of rain, and roughly 6 days with 6+ hours of sunshine this month.
Cardiff mixes a Victorian arcades core, Cardiff Castle, and bay regeneration with easy access to Welsh coast and valleys. Best window: late spring through early autumn.
September in Cardiff: mixed conditions, plan around the weather
Temperatures hover around 15°C (60°F) — the kind of month where neither heat nor cold forces the schedule.
Budget for roughly 96 mm of rain this month — a flexible day or two helps — with about 6 days with 6+ hours of sunshine and 12.4 hours of daylight to work around it.
That is 6.7/10 on the same scale — 6th of 12 months, versus 9/10 for the best month here.
Pack layers you can shed by midday plus one warm layer for the evening, a packable rain layer.
Expect mid-season pricing, and crowds are moderate.
If your dates are flexible, June is materially better in Cardiff — 2.3 points higher on the same scale.
Frequently asked
- What is the weather like in Cardiff in September?
- In September, Cardiff averages 15°C, 96 mm of rain, and about 6 days with 6+ hours of sunshine. Its climate-comfort score is 6.7/10.
- Is September a good time to visit Cardiff?
- September earns a 6.7/10 climate-comfort score. Use the year-round chart to weigh the weather against your budget and crowd preferences.
- How much does it rain in Cardiff in September?
- Expect about 96 mm of rain in September. Average humidity is 85% and there are about 6 days with 6+ hours of sunshine.
Curated in Cardiff
Tickets & experiences
Things to do in Cardiff
Cardiff, United Kingdom. Live activities and tours from GetYourGuide, matched to this destination.