September weather forecast and climate
Saint Peter Port, Guernsey

A calm sunny day in Saint Peter Port, Guernsey, with ships docked at the harbor
A calm sunny day in Saint Peter Port, Guernsey, with ships docked at the harbor

Weather in September

The first month of the autumn, September, is still a comfortable month in Saint Peter Port, Guernsey, with average temperature fluctuating between 17.2°C (63°F) and 15.4°C (59.7°F).

Temperature

In Saint Peter Port, Guernsey, the average high-temperature is almost the same as in August - a still comfortable 17.2°C (63°F). In September, in Saint Peter Port, the average low-temperature is 15.4°C (59.7°F).

Humidity

In September, the average relative humidity is 80%.

Rainfall

In September, in Saint Peter Port, the rain falls for 13.5 days. Throughout September, 31mm (1.22") of precipitation is accumulated. In Saint Peter Port, during the entire year, the rain falls for 196.3 days and collects up to 557mm (21.93") of precipitation.

Snowfall

February through December are months without snowfall in Saint Peter Port.

Sea temperature

In Saint Peter Port, the average water temperature is 16°C (60.8°F).
Note: Swimming in 16°C (60.8°F) is not enjoyable for the majority. Controlling breathing becomes progressively more difficult as surface water temperature decreases below 21°C (69.8°F).

Daylight

In Saint Peter Port, the average length of the day in September is 12.6h.

Sunshine

In Saint Peter Port, Guernsey, the average sunshine is 8.4h.

UV index

July through September, with an average maximum UV index of 5, are months with the highest UV index. A UV Index value of 3 to 5 symbolizes a medium vulnerability from the exposure to the Sun's UV rays for ordinary individuals.
Note: In September, the average maximum UV index of 5 translate into the following recommendations:
Take precautions - Protection against the skin and eye damage is obliged. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
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FAQ

What is the temperature in September in Saint Peter Port?

The average high-temperature, in September, in Saint Peter Port, is 17.2°C (63°F), while the average low-temperature is 15.4°C (59.7°F).

What is the average humidity in September in Saint Peter Port?

In Saint Peter Port, Guernsey, the average relative humidity in September is 80%.

How many days does it rain in September in Saint Peter Port?

In Saint Peter Port, in September, during 13.5 rainfall days, 31mm (1.22") of precipitation is typically accumulated.

When it does not snow in Saint Peter Port?

In Saint Peter Port, Guernsey, snow does not fall in February through December.

What is the sea temperature in September in Saint Peter Port?

In September, the average sea temperature in Saint Peter Port, Guernsey, is 16°C (60.8°F). For swimming, a surface water temperature of 16°C (60.8°F) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 21°C (69.8°F).

What is the average length of the day in September in Saint Peter Port?

In Saint Peter Port, Guernsey, the average length of the day in September is 12.6h.

How long on average sun shines in September in Saint Peter Port?

In September, the average sunshine is 8.4h.

When is the highest UV index in Saint Peter Port?

Months with the highest UV index in Saint Peter Port, Guernsey, are July through September, with an average maximum UV index of 5.

How high is the UV index in September in Saint Peter Port?

In Saint Peter Port, the average daily maximum UV index in September is 5. A UV Index reading of 3 to 5 represents a medium health risk from the exposure to the Sun's UV radiation.

Average temperature in September
Saint Peter Port, Guernsey

Average temperature in September - Saint Peter Port, 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).

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Average pressure in September
Saint Peter Port, Guernsey

Average pressure in September - Saint Peter Port, 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).

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Average wind speed in September
Saint Peter Port, Guernsey

Average wind speed in September - Saint Peter Port, 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).

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Average humidity in September
Saint Peter Port, Guernsey

Average humidity in September - Saint Peter Port, Guernsey
  • Average humidity in September: 80%

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

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Average rainfall in September
Saint Peter Port, Guernsey

Average rainfall in September - Saint Peter Port, 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).

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Average rainfall days in September
Saint Peter Port, Guernsey

Average rainfall days in September - Saint Peter Port, 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).

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Average snowfall in September
Saint Peter Port, Guernsey

Average snowfall in September - Saint Peter Port, Guernsey
  • Average snowfall in September: 0mm

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

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Average snowfall days in September
Saint Peter Port, Guernsey

Average snowfall days in September - Saint Peter Port, Guernsey
  • Average snowfall days in September: 0 days

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

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Average sea temperature in September
Saint Peter Port, Guernsey

Average sea temperature in September - Saint Peter Port, Guernsey
  • Average sea temperature in September: 16°C

The best month for swimming (with the highest average sea temperature) is August (17°C).
The coldest months (with the lowest average sea temperature) are February and March (9°C).

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Average daylight in September /
Average sunshine in September
Saint Peter Port, Guernsey

Average daylight in September / Average sunshine in September - Saint Peter Port, Guernsey
  • Average daylight in September: 12.6h

The month with the longest days is June (Average daylight: 16.2h).
The month with the shortest days is December (Average daylight: 8.3h).

  • Average sunshine in September: 8.4h

The month with the most sunshine is July (Average sunshine: 9.7h).
Months with the least sunshine are January, November and December (Average sunshine: 3.9).

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Average sunshine days in September
Saint Peter Port, Guernsey

Average sunshine days in September - Saint Peter Port, 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).

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Average UV index in September
Saint Peter Port, Guernsey

Average UV index in September - Saint Peter Port, Guernsey
  • Average UV index in September: 5

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).

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Average cloud cover in September
Saint Peter Port, Guernsey

Average cloud cover in September - Saint Peter Port, Guernsey
  • Average cloud cover in September: 41

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).

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Average visibility in September
Saint Peter Port, Guernsey

Average visibility in September - Saint Peter Port, Guernsey
  • Average visibility in September: 10km

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

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