Belfast Weather in September
With daytime temperatures of 17°C (63°F) and nighttime lows of 11°C (52°F), September in Belfast brings moderate temperatures during the day. Do keep in mind that quite a bit of rainfall is typical. Around 83 mm (3.3 in) falls on average.
Rainfall in Belfast in September
Records from the past 30 years suggest around 17 days of rain, with 83 mm (3.3 in) average for the month. This is a month with many wet days but modest rainfall totals, so showers are generally light and easy to manage.
Temperature in Belfast in September
Daytime highs in Belfast in September reach 17°C (63°F), with nights around 11°C (52°F). The summer season takes place during September. This creates a mild day-to-night pattern that is generally easy to manage with the right clothing. With overnight lows of 11°C (52°F), evenings can feel noticeably cooler than the daytime. An extra layer is a good idea, though the cool air makes for a good night's sleep.
Sunshine in Belfast in September
With about 109 hours of sunshine, the area enjoys a nice balance of sun and overcast, creating a pleasant environment.
Wind Speed in Belfast in September
September sees wind speeds averaging 4 m/s (8 knots). You'll experience variable conditions with moderate winds that create small waves on water and keep branches moving. Conditions range from light winds to moderate breezes throughout the month.
Average water temperature in September
With water at 13°C (55°F), it's on the cooler side. Keen swimmers won't be put off, but those who prefer warm water may find it less enjoyable.If you prefer dry days with pleasant temperatures, July and August typically offer the best circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United Kingdom, check out our Belfast's climate page.
Belfast Temperature in September
Min Temperature
11°C (52°F)
Max Temperature
17°C (63°F)
Water Temperature
13°C (55°F) *
Chance of Rain
58%
Precipitation
83 mm (3.3 in)
Rainy days
17 days
Humidity
91% *
Windspeed
4 m/s (8 knots) *
Sunshine
109 hours *
Percentage Sunshine
28% *
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Belfast typically stay consistent throughout September, with daily highs averaging around 17°C (63°F). Nights are cool, with lows typically ranging from 9°C (48°F) to 11°C (52°F).
Average temperatures in September
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in September
Historical weather for Belfast in September
Browse day-by-day weather records for Belfast spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Belfast historical weather extremes in September
According to our 49 years of weather records for Belfast, the following extremes were recorded between 1976 and 2025.
- Belfast recorded its highest September temperature of 25°C (77°F) on September 8, 2023.
- The lowest daytime temperature in September was 10°C (50°F), recorded on September 21, 1990.
- Nighttime temperatures dropped to 1°C (34°F) on September 26, 1984, marking the coldest September night on record.
- The wettest day in September Belfast was on September 24, 2012 with 24 mm (0.9 in) of precipitation.
Best Places in the United Kingdom in September
Find out more about the weather in the United Kingdom and which places have the best travel conditions in this month. See all of the United Kingdom in September →
perfect weather
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unpleasant
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What to Wear in Belfast in September
Pleasant temperatures in September mean you can pack light but flexibel pieces. Think cotton t-shirts, comfortable walking shorts, and one warmer layer for evenings. A light sweater or denim jacket works well. Prepare for significant rainfall with proper waterproof clothing and shoes. The water temperature sits at about 13°C (55°F), which is too chilly for most people to enjoy swimming. Leave the swimsuit at home unless you love cold water. Bring sunglasses since you'll have some sunny periods throughout the monthWhat To Do in Belfast in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United Kingdom, check out our Belfast's climate page.
Temperature Rainfall Sunshine Humidity Wind Speed Water Temp
See the full Belfast climate overview or explore weather in the United Kingdom.
