Average temperatures, rainfall and packing tips for Belfast, United Kingdom in September
September in Belfast is typically mild, with average daytime highs around 15°C and nights near 9°C. Temperature-wise it sits mid-range for Belfast (the 5th warmest month).
Expect some rain: around 60 mm falls in Belfast during September on average.
If your dates are flexible, the most comfortable months in Belfast are usually July and August.
← Belfast weather tomorrow (live)
In September, Belfast averages a daytime high of about 15°C and a night-time low of around 9°C, based on recent historical data.
Expect some rain: around 60 mm falls in Belfast during September on average.
September is a workable time to visit Belfast, with mild days - just pack accordingly. If your dates are flexible, the most comfortable months in Belfast are usually July and August.