Average temperatures, rainfall and packing tips for Cardiff, United Kingdom in September
September in Cardiff is typically mild, with average daytime highs around 17°C and nights near 11°C. Temperature-wise it sits mid-range for Cardiff (the 5th warmest month).
September is one of the wetter months in Cardiff, with around 198 mm of rain - plan around showers.
If your dates are flexible, the most comfortable months in Cardiff are usually June, July and August.
← Cardiff weather tomorrow (live)
In September, Cardiff averages a daytime high of about 17°C and a night-time low of around 11°C, based on recent historical data.
September is one of the wetter months in Cardiff, with around 198 mm of rain - plan around showers.
September is a workable time to visit Cardiff, with mild days - just pack accordingly. If your dates are flexible, the most comfortable months in Cardiff are usually June, July and August.