September weather forecast
Grand Fort, Guernsey

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Weather in September

As Grand Fort, Guernsey enters autumn, September makes a clear break from the summer weather. Temperature starts to descend, along with a decrease in sunlight hours making the days shorter. Despite the drop in temperature, humidity remains almost constant since August. The wind speed sees a noticeable rise to 25.8km/h (16mph), which adds a significant nip to the air. The earliest signs of autumn are evident as rainfall increases to 31mm (1.22"), giving a greener appeal to the city.

Temperature

The commencement of September brings an average high-temperature of a still enjoyable 17.2°C (63°F), marking an inconsequential divergence from August. In September, Grand Fort's nights cool slightly to a consistent average temperature of 15.4°C (59.7°F).

Humidity

In Grand Fort, the average relative humidity in September is 80%.

Rainfall

In Grand Fort, during September, the rain falls for 13.5 days and regularly aggregates up to 31mm (1.22") of precipitation. Throughout the year, there are 196.3 rainfall days, and 557mm (21.93") of precipitation is accumulated.

Snowfall

February through December are months without snowfall in Grand Fort.

Daylight

The average length of the day in September is 12h and 36min.
On the first day of September in Grand Fort, sunrise is at 06:26 and sunset at 19:53. On the last day of the month, sunrise is at 07:09 and sunset at 18:50 BST.

Sunshine

In September, the average sunshine is 8.4h.

UV index

The months with the highest UV index are July through September, with an average maximum UV index of 5. A UV Index reading of 3 to 5 represents a medium health hazard from unsafe exposure to UV radiation for the average person.
Note: A daily maximum UV index of 5 in September translates into the following instructions:
Take care. Persons with lighter skin might suffer burns in less than 30 minutes. Solar radiation is at its peak intensity during midday, so it's advisable to stay indoors or in the shade. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage.

Frequently asked questions

What are September temperatures in Grand Fort?

The high-temperature, in September, in Grand Fort, is 17.2°C (63°F), while the low-temperature averages to 15.4°C (59.7°F).

What is the average humidity in September in Grand Fort?

In September, the average relative humidity in Grand Fort, Guernsey, is 80%.

How many days does it rain in September in Grand Fort?

In Grand Fort, in September, it is raining for 13.5 days, with typically 31mm (1.22") of accumulated precipitation.

When it does not snow in Grand Fort?

February through December are months without snowfall in Grand Fort, Guernsey.

How many hours of daylight does Grand Fort have in September?

In Grand Fort, the average day length in September is 12h and 36min.

When is the sunrise / sunset in September in Grand Fort?

In September, on the first day of the month, sunrise is at 06:26 and sunset at 19:53. On the last day of the month, in Grand Fort, sunrise is at 07:09 and sunset at 18:50 BST.

How many hours of sunshine does Grand Fort have in September?

In September, the average sunshine duration in Grand Fort, Guernsey, is 8.4h.

What are the months with the highest UV index in Grand Fort?

The months with the highest UV index are July through September, with an average maximum UV index of 5.

How high is the UV index in September in Grand Fort?

In September, the average daily maximum UV index in Grand Fort, Guernsey, is 5. A UV Index reading of 3 to 5 represents a moderate vulnerability from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover

Average temperature in September
Grand Fort, Guernsey

Average temperature in September - Grand Fort, Guernsey
  • Average high temperature in September: 17.2°C

The warmest month (with the highest average high temperature) is August (17.8°C).
The month with the lowest average high temperature is February (9.2°C).

  • Average low temperature in September: 15.4°C

The month with the highest average low temperature is August (15.8°C).
The coldest month (with the lowest average low temperature) is February (7°C).

Average pressure in September
Grand Fort, Guernsey

Average pressure in September - Grand Fort, Guernsey
  • Average pressure in September: 1017.9mbar

The month with the highest atmospheric pressure is September (1017.9mbar).
The month with the lowest atmospheric pressure is November (1011.5mbar).

Average wind speed in September
Grand Fort, Guernsey

Average wind speed in September - Grand Fort, Guernsey
  • Average wind speed in September: 25.8km/h

The windiest month (with the highest average wind speed) is December (36km/h).
The calmest month (with the lowest average wind speed) is July (21.9km/h).

Average humidity in September
Grand Fort, Guernsey

Average humidity in September - Grand Fort, Guernsey
  • Average humidity in September: 80%

The months with the highest relative humidity are June and July (84%).
The months with the lowest relative humidity are November and December (77%).

Average rainfall in September
Grand Fort, Guernsey

Average rainfall in September - Grand Fort, Guernsey
  • Average rainfall in September: 31mm

The wettest month (with the highest rainfall) is November (87mm).
The driest month (with the least rainfall) is July (26mm).

Average rainfall days in September
Grand Fort, Guernsey

Average rainfall days in September - Grand Fort, Guernsey
  • Average rainfall days in September: 13.5 days

The month with the highest number of rainy days is November (22.8 days).
The month with the least rainy days is June (11.5 days).

Average snowfall in September
Grand Fort, Guernsey

Average snowfall in September - Grand Fort, Guernsey
  • Average snowfall in September: 0mm

The month with the highest snowfall is January (2mm).
The months with the least snowfall are February, March, April, May, June, July, August, September, October, November and December (0mm).

Average snowfall days in September
Grand Fort, Guernsey

Average snowfall days in September - Grand Fort, Guernsey
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (0.3 days).
The months with the least snowfall days are March, April, May, June, July, August, September, October, November and December (0 days).

Average daylight in September /
Average sunshine in September
Grand Fort, Guernsey

Average daylight in September / Average sunshine in September - Grand Fort, Guernsey
  • Average daylight in September: 12h and 4min

The month with the longest days is June (Average daylight: 16h and 12min).
The month with the shortest days is December (Average daylight: 8h and 12min).

  • Average sunshine in September: 8h and 2min

The month with the most sunshine is July (Average sunshine: 9h and 42min).
The months with the least sunshine are January, November and December (Average sunshine: 3h and 54min).

Average sunshine days in September
Grand Fort, Guernsey

Average sunshine days in September - Grand Fort, Guernsey
  • Average sunshine days in September: 13.1 days

The month with the most sunshine days is May (16.3 days).
The month with the least sunshine days is November (4 days).

Average UV index in September
Grand Fort, Guernsey

Average UV index in September - Grand Fort, Guernsey
  • Average UV index in September: 5

The months with the highest UV index are July, August and September (UV index 5).
The month with the lowest UV index is February (UV index 2).

Average cloud cover in September
Grand Fort, Guernsey

Average cloud cover in September - Grand Fort, Guernsey
  • Average cloud cover in September: 41

The months with the most cloud cover are November and December (Cloud cover 63).
The month with the least cloud cover is July (Cloud cover 37).

Average visibility in September
Grand Fort, Guernsey

Average visibility in September - Grand Fort, Guernsey
  • Average visibility in September: 10km

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (10km).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (10km).

Grand Fort, Guernsey

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