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
As Holyhead welcomes September, the average high-temperature is noted at a moderate 15.5°C (59.9°F), closely aligning with the preceding month. Holyhead encounters a small divergence from daytime high temperatures, averaging a low-temperature of 13.5°C (56.3°F) during September nights.Humidity
The average relative humidity in September in Holyhead is 81%.Rainfall
In September, the rain falls for 19.5 days. Throughout September, 61mm (2.4") of precipitation is accumulated. In Holyhead, during the entire year, the rain falls for 233.6 days and collects up to 739mm (29.09") of precipitation.Snowfall
April through October are months without snowfall.Sea temperature
September is the month with the warmest seawater, with an average sea temperature of 15.2°C (59.4°F).Note: Most individuals do not find swimming at 15.2°C (59.4°F) to be enjoyable. As the water temperature declines below 21°C (69.8°F), maintaining control over one's breathing becomes harder.
Daylight
In September, the average length of the day is 12h and 41min.On the first day of September, sunrise is at 6:29 am and sunset at 8:07 pm. On the last day of the month, sunrise is at 7:19 am and sunset at 6:57 pm BST.
Sunshine
In September, the average sunshine in Holyhead is 6.8h.UV index
The months with the highest UV index are May through September, with an average maximum UV index of 4. A UV Index reading of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for ordinary individuals.Note: A maximum UV index of 4 in September translates into the following recommendations:
Take necessary precautions - Protection from skin and eye injury is mandatory. Around midday, solar radiation is most harmful; hence, exposure should be limited. Sun protection is enhanced with clothing that boasts a tight weave yet offers a loose fit.
Frequently asked questions
What are September temperatures in Holyhead?
What is the average humidity in September in Holyhead?
How many days does it rain in September in Holyhead?
When it does not snow in Holyhead?
When is the sea warmest in Holyhead?
What is the sea water temperature in September in Holyhead?
What is the average length of the day in September in Holyhead?
What time are sunrise and sunset in September in Holyhead?
How many hours of sunshine does Holyhead have in September?
What are the months with the highest UV index in Holyhead?
How high is the UV index in September in Holyhead?
Average temperature in September
Holyhead, United Kingdom
- Average high temperature in September: 15.5°C
The warmest month (with the highest average high temperature) is August (16.6°C).
The month with the lowest average high temperature is February (7.8°C).
- Average low temperature in September: 13.5°C
The month with the highest average low temperature is August (14.3°C).
The coldest month (with the lowest average low temperature) is February (5.8°C).
Average pressure in September
Holyhead, United Kingdom
- Average pressure in September: 1015.6mbar
The month with the highest atmospheric pressure is May (1016.1mbar).
The month with the lowest atmospheric pressure is November (1008.7mbar).
Average wind speed in September
Holyhead, United Kingdom
- Average wind speed in September: 23.5km/h
The windiest month (with the highest average wind speed) is December (31.3km/h).
The calmest month (with the lowest average wind speed) is June (18.7km/h).
Average humidity in September
Holyhead, United Kingdom
- Average humidity in September: 81%
The months with the highest relative humidity are July and August (84%).
The month with the lowest relative humidity is November (79%).
Average rainfall in September
Holyhead, United Kingdom
- Average rainfall in September: 61mm
The wettest month (with the highest rainfall) is November (87mm).
The driest month (with the least rainfall) is May (36mm).
Average rainfall days in September
Holyhead, United Kingdom
- Average rainfall days in September: 19.5 days
The month with the highest number of rainy days is August (23.4 days).
The month with the least rainy days is April (15.6 days).
Average snowfall in September
Holyhead, United Kingdom
- Average snowfall in September: 0mm
The months with the highest snowfall are January and December (4mm).
The months with the least snowfall are April, May, June, July, August, September and October (0mm).
Average snowfall days in September
Holyhead, United Kingdom
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (1 days).
The months with the least snowfall days are April, May, June, July, August, September and October (0 days).
Average sea temperature in September
Holyhead, United Kingdom
- Average sea temperature in September: 15.2°C
The best month for swimming (with the highest average sea temperature) is September (15.2°C).
The coldest month (with the lowest average sea temperature) is March (8.3°C).
Average daylight in September /
Average sunshine in September
Holyhead, United Kingdom
- Average daylight in September: 12h and 4min
The month with the longest days is June (Average daylight: 16h and 54min).
The month with the shortest days is December (Average daylight: 7h and 36min).
- Average sunshine in September: 6h and 5min
The month with the most sunshine is May (Average sunshine: 8h and 30min).
The month with the least sunshine is December (Average sunshine: 3h and 36min).
Average sunshine days in September
Holyhead, United Kingdom
- Average sunshine days in September: 8.1 days
The month with the most sunshine days is May (12.3 days).
The month with the least sunshine days is December (4.3 days).
Average UV index in September
Holyhead, United Kingdom
- Average UV index in September: 4
The months with the highest UV index are May, June, July, August and September (UV index 4).
The months with the lowest UV index are January, February and December (UV index 2).
Average cloud cover in September
Holyhead, United Kingdom
- Average cloud cover in September: 53
The month with the most cloud cover is December (Cloud cover 65).
The month with the least cloud cover is May (Cloud cover 46).
Average visibility in September
Holyhead, United Kingdom
- Average visibility in September: 10km
The months with the highest visibility are February, March, April, May, June, July, August, September, October, November and December (10km).
The month with the lowest visibility is January (9km).
Holyhead, United Kingdom
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