September weather forecastBelfast, United Kingdom
September weather for Belfast, United Kingdom: The month with the warmest seawater in Belfast, United Kingdom, is September, with an average sea temperature of 14.3°C (57.7°F). In Belfast, United Kingdom, in September, it is raining for 16.4 days, with typically 40mm (1.57") of accumulated precipitation.
September
Weather in September
In September, Belfast's weather conditions start to cool off compared to the preceding summer months. Despite the transition to autumn, sea temperatures are still relatively higher, making water activities plausible. The days continue to shorten as autumn approaches, yet sufficient daylight hours render the days pleasant. As the temperature lowers, the rainfall decreases to a more manageable 40mm (1.57"). As such, September balances the end of summer warmth with the advent of autumn chill, coupled with decent rainfall.Temperature
Belfast, United Kingdom, records an average high-temperature of a still refreshing 14.8°C (58.6°F) in September, maintaining a close correlation with August's 16.7°C (62.1°F). Belfast documents a consistent average low-temperature of 10.1°C (50.2°F) at night during September.Humidity
In September, the average relative humidity is 87%.Rainfall
In Belfast, in September, during 16.4 rainfall days, 40mm (1.57") of precipitation is typically accumulated. In Belfast, during the entire year, the rain falls for 220.2 days and collects up to 626mm (24.65") of precipitation.Snowfall
In Belfast, snow does not fall in April through October.Sea temperature
The month with the warmest seawater in Belfast is September, with an average sea temperature of 14.3°C (57.7°F).Note: Swimming in 14.3°C (57.7°F) is deemed hazardous. Exposure to temperatures below 10°C (50°F) leads to immediate severe cold shock and hyperventilation.
Daylight
In Belfast, the average length of the day in September is 12h and 43min.On the first day of the month, sunrise is at 6:32 am and sunset at 8:15 pm. On the last day of September, in Belfast, sunrise is at 7:25 am and sunset at 7:01 pm BST.
Sunshine
In Belfast, the average sunshine in September is 6h.UV index
In Belfast, the average daily maximum UV index in September is 3. A UV Index value of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for the ordinary person.Note: A maximum high daily UV index of 3 during September translates into the following directions:
Undertake protective steps - Preventing sun damage is advised. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. In bright sunlight, prioritize sunglasses that grant protection from UVA and UVB radiation.
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Belfast, United Kingdom
- Average high temperature in September: 14.8°C
The warmest month (with the highest average high temperature) is July (16.9°C).
The month with the lowest average high temperature is January (6.8°C).
- Average low temperature in September: 10.1°C
The month with the highest average low temperature is August (11.3°C).
The coldest month (with the lowest average low temperature) is February (2.8°C).
Average pressure in September
Belfast, United Kingdom
- Average pressure in September: 1014.2mbar
The month with the highest atmospheric pressure is May (1015.6mbar).
The month with the lowest atmospheric pressure is November (1007.3mbar).
Average wind speed in September
Belfast, United Kingdom
- Average wind speed in September: 17km/h
The windiest month (with the highest average wind speed) is January (21.3km/h).
The calmest months (with the lowest average wind speed) are June and July (13.7km/h).
Average humidity in September
Belfast, United Kingdom
- Average humidity in September: 87%
The months with the highest relative humidity are January and December (88%).
The months with the lowest relative humidity are April and May (83%).
Average rainfall in September
Belfast, United Kingdom
- Average rainfall in September: 40mm
The wettest month (with the highest rainfall) is August (72mm).
The driest month (with the least rainfall) is May (38mm).
Average rainfall days in September
Belfast, United Kingdom
- Average rainfall days in September: 16.4 days
The month with the highest number of rainy days is August (23 days).
The month with the least rainy days is April (16.1 days).
Average snowfall in September
Belfast, United Kingdom
- Average snowfall in September: 0mm
The month with the highest snowfall is February (25mm).
The months with the least snowfall are April, May, June, July, August, September and October (0mm).
Average snowfall days in September
Belfast, United Kingdom
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (2.8 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).
Average sea temperature in September
Belfast, United Kingdom
- Average sea temperature in September: 14.3°C
The best month for swimming (with the highest average sea temperature) is September (14.3°C).
The coldest month (with the lowest average sea temperature) is March (8°C).
Average daylight in September /
Average sunshine in September
Belfast, United Kingdom
- Average daylight in September: 12h and 42min
The month with the longest days is June (Average daylight: 17h and 12min).
The month with the shortest days is December (Average daylight: 7h and 24min).
- Average sunshine in September: 6h and 0min
The month with the most sunshine is June (Average sunshine: 7h and 18min).
The month with the least sunshine is February (Average sunshine: 3h and 30min).
Average sunshine days in September
Belfast, United Kingdom
- Average sunshine days in September: 8.4 days
The month with the most sunshine days is April (11.5 days).
The month with the least sunshine days is August (5.6 days).
Average UV index in September
Belfast, United Kingdom
- Average UV index in September: 3
The months with the highest UV index are May, June, July and August (UV index 4).
The months with the lowest UV index are January, February, March, November and December (UV index 2).
Average cloud cover in September
Belfast, United Kingdom
- Average cloud cover in September: 58
The months with the most cloud cover are January and February (Cloud cover 63).
The month with the least cloud cover is April (Cloud cover 55).
Average visibility in September
Belfast, United Kingdom
- Average visibility in September: 9km
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (9km).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (9km).
