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.

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit Ireland, check out our Belfast's climate page.

Belfast Temperature in September

Min Temperature 10°C (50°F)  

Max Temperature 17°C (63°F)  

Water Temperature 13°C (55°F)  

Chance of Rain 63%  

Precipitation 77 mm (3 in)  

Rainy days 19 days  

Humidity 91%  

Windspeed 4 m/s (8 knots)  

Sunshine 109 hours  

Percentage Sunshine 28%  

What to Wear in Belfast in September

For Belfast in September, you'll want flexible clothing. It's wise to pack cotton shirts, comfortable shorts, and a pair of jeans for cooler evenings. A light sweater or jacket is useful for air-conditioned spaces (like buses) or unexpected cool moments. Rain is likely on several days, so bring a good rain jacket. With water temperatures around 13°C (55°F), the water is quite cold for swimming. You can skip the swimwear unless you're particularly tough. Bring sunglasses since you'll have some sunny periods throughout the month

What To Do in Belfast in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Swimming

6/10

Cycling

6/10

Walking

6/10

Camping

8/10

Outdoor sports

9/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit Ireland, check out our Belfast's climate page.

More climate data for Belfast

Temperature Rainfall Sunshine Humidity Wind Speed Water Temp

See the full Belfast climate overview or explore weather in Ireland.