Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average sea temperature in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
September brings an average high-temperature of a still refreshing 14.7°C (58.5°F), nearly identical to the preceding month. The nights of September in Portstewart anticipate a slight dip from daytime high temperatures, settling to an average low-temperature of 10.7°C (51.3°F).Humidity
In Portstewart, the average relative humidity in September is 85%.Rainfall
In Portstewart, during September, the rain falls for 19.6 days and regularly aggregates up to 40mm (1.57") of precipitation. Throughout the year, there are 238.3 rainfall days, and 632mm (24.88") of precipitation is accumulated.Snowfall
May through October are months without snowfall in Portstewart.Sea temperature
In Portstewart, the average seawater temperature in September is 14.2°C (57.6°F).Note: Swimming in 14.2°C (57.6°F) is considered life-threatening. Even a few minutes in 13°C (55.4°F) water is uncomfortable, and swimming below 10°C (50°F) may cause total loss of breathing control and cold shock, depending on a person's physique.
Daylight
In Portstewart, the average length of the day in September is 12h and 43min.On the first day of the month, sunrise is at 6:34 am and sunset at 8:19 pm. On the last day of September, in Portstewart, sunrise is at 7:28 am and sunset at 7:04 pm BST.
Sunshine
In Portstewart, United Kingdom, the average sunshine in September is 6h.UV index
The months with the highest UV index in Portstewart are May, June, August and September, with an average maximum UV index of 4. A UV Index of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for ordinary individuals.Note: An average maximum UV index of 4 in September leads to these recommendations:
Heed the precautions - Suggestions to avoid sunburn are made. When the Sun is at its strongest around midday, find shade and limit exposure. Using UVA and UVB-protective sunglasses and sun-protective clothing is effective against UV radiation.
Frequently asked questions
What are the temperatures in Portstewart in September?
What is the average humidity in September in Portstewart?
How much does it rain in Portstewart in September?
When it does not snow in Portstewart?
What is the water temperature in September in Portstewart?
What is the average length of the day in September in Portstewart?
When is the sunrise / sunset in September in Portstewart?
How long on average sun shines in September in Portstewart?
When is the highest UV index in Portstewart?
What is the UV index intensity in September in Portstewart?
Average temperature in September
Portstewart, United Kingdom
- Average high temperature in September: 14.7°C
The warmest month (with the highest average high temperature) is July (16°C).
The month with the lowest average high temperature is January (7.1°C).
- Average low temperature in September: 10.7°C
The month with the highest average low temperature is August (11.8°C).
The coldest month (with the lowest average low temperature) is February (4°C).
Average pressure in September
Portstewart, United Kingdom
- Average pressure in September: 1013.5mbar
The month with the highest atmospheric pressure is May (1015.2mbar).
The month with the lowest atmospheric pressure is November (1006.6mbar).
Average wind speed in September
Portstewart, United Kingdom
- Average wind speed in September: 21.1km/h
The windiest month (with the highest average wind speed) is January (27.5km/h).
The calmest month (with the lowest average wind speed) is July (16.7km/h).
Average humidity in September
Portstewart, United Kingdom
- Average humidity in September: 85%
The months with the highest relative humidity are July and August (86%).
The month with the lowest relative humidity is April (81%).
Average rainfall in September
Portstewart, United Kingdom
- Average rainfall in September: 40mm
The wettest months (with the highest rainfall) are July and August (74mm).
The driest month (with the least rainfall) is April (35mm).
Average rainfall days in September
Portstewart, United Kingdom
- Average rainfall days in September: 19.6 days
The month with the highest number of rainy days is August (24 days).
The month with the least rainy days is April (16.8 days).
Average snowfall in September
Portstewart, United Kingdom
- Average snowfall in September: 0mm
The month with the highest snowfall is February (16mm).
The months with the least snowfall are May, June, July, August, September and October (0mm).
Average snowfall days in September
Portstewart, United Kingdom
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (2.5 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average sea temperature in September
Portstewart, United Kingdom
- Average sea temperature in September: 14.2°C
The best month for swimming (with the highest average sea temperature) is August (14.3°C).
The coldest month (with the lowest average sea temperature) is March (8.3°C).
Average daylight in September /
Average sunshine in September
Portstewart, United Kingdom
- Average daylight in September: 12h and 4min
The month with the longest days is June (Average daylight: 17h and 18min).
The month with the shortest days is December (Average daylight: 7h and 12min).
- Average sunshine in September: 6h and 0min
The month with the most sunshine is June (Average sunshine: 8h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).
Average sunshine days in September
Portstewart, United Kingdom
- Average sunshine days in September: 6.3 days
The month with the most sunshine days is April (9.8 days).
The month with the least sunshine days is August (4.2 days).
Average UV index in September
Portstewart, United Kingdom
- Average UV index in September: 4
The months with the highest UV index are May, June, August and September (UV index 4).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Portstewart, United Kingdom
- Average cloud cover in September: 58
The month with the most cloud cover is January (Cloud cover 63).
The month with the least cloud cover is April (Cloud cover 52).
Average visibility in September
Portstewart, United Kingdom
- Average visibility in September: 9km
The month with the highest visibility is November (10km).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October and December (9km).
Portstewart, United Kingdom
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