Belfast Weather in September

Thinking of visiting Belfast in September? Expect moderate temperatures reaching 17°C (63°F) during the day, dropping to 10°C (50°F) at night, and note that quite a bit of rainfall is likely.

Rainfall in Belfast in September

Historically, the month has about 19 days of rain, averaging 77 mm (3 in) in total. Rain is frequent but mostly light this month, with brief showers more common than heavy downpours.

Temperature in Belfast in September

Daytime temperatures in Belfast reach 17°C (63°F) in September, dropping to 10°C (50°F) at night. Even when the weather is stable, mornings and evenings can still feel distinctly cool. Nights drop to around 10°C (50°F), which is noticeably cooler than the daytime. A light jacket for the evening is a sensible addition, and the cool nights tend to make sleeping comfortable.

Sunshine in Belfast in September

The area experiences a moderate amount of sunshine, with approximately 109 hours of sunlight expected. This means a decent mix of sun and overcast.

Wind Speed in Belfast in September

Wind speeds average 4 m/s (8 knots) during September. At this speed, expect moderate winds that can raise dust and move small branches. Since this is an average, some days have gentle light winds while others experience stronger breezes that are quite noticeable.

Average water temperature in September

The water temperature is 13°C (55°F), chilly, but perfectly fine for a swim if you're not too sensitive to cold water. A short wetsuit can make longer sessions more comfortable.

If your ideal day consists of dry skies and pleasant temperatures, July typically offers the best circumstances for Belfast.