Saint Peter Port
Guernsey
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Saint Peter Port, Guernsey

A calm sunny day in Saint Peter Port, Guernsey, with ships docked at the harbor, and a clear skyline in the horizon
A calm sunny day in Saint Peter Port, Guernsey, with ships docked at the harbor, and a clear skyline in the horizon
September, the first month of the autumn, in Saint Peter Port, is also an enjoyable month, with average temperature ranging between max 18°C (64.4°F) and min 13°C (55.4°F).

Temperature

In Saint Peter Port, Guernsey, the average high-temperature is practically the same as in August - an enjoyable 18°C (64.4°F). In September, in Saint Peter Port, the average low-temperature is 13°C (55.4°F).

Rainfall

In September, the rain falls for 13 days. Throughout September, 63mm (2.5") of precipitation is accumulated. In Saint Peter Port, during the entire year, the rain falls for 175 days and collects up to 799mm (31.5") of precipitation.

Sea temperature

In Saint Peter Port, the average seawater 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

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

Sunshine

The average sunshine in Saint Peter Port is 6h.

UV index

The average daily maximum UV index in Saint Peter Port is 4. A UV Index reading of 3 to 5 represents a medium vulnerability from unprotected exposure to the Sun's UV rays for the average person.
Note: In September, the average maximum UV index of 4 translate into the following recommendations:
Take precautions. Light skin individuals may get burned in less than 30 minutes. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.

What is the temperature in September in Saint Peter Port?

In Saint Peter Port, Guernsey, in September, the average high-temperature is 18°C (64.4°F), and the average low-temperature is 13°C (55.4°F).

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

In Saint Peter Port, during September, the rain falls for 13 days and regularly aggregates up to 63mm (2.5") of precipitation.

How cold is the water in September in Saint Peter Port?

In Saint Peter Port, Guernsey, in September, the average water temperature 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).

How many hours of daylight does Saint Peter Port have in September?

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

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

In Saint Peter Port, the average sunshine in September is 6h.

What is the UV index intensity in September in Saint Peter Port?

In September, the average daily maximum UV index in Saint Peter Port is 4. A UV Index reading of 3 to 5 represents a moderate health threat from unprotected exposure to the UV radiation.
Average temperature in September - Saint Peter Port, Guernsey
  • Average high temperature in September: 18°C

The warmest month (with the highest average high temperature) is August (20°C).
The month with the lowest average high temperature is February (8°C).

  • Average low temperature in September: 13°C

The month with the highest average low temperature is August (14°C).
The coldest month (with the lowest average low temperature) is February (4°C).

Average rainfall in September - Saint Peter Port, Guernsey
  • Average rainfall in September: 63mm

The wettest month (with the highest rainfall) is December (100mm).
The driest month (with the lowest rainfall) is July (37mm).

Average rainfall days in September - Saint Peter Port, Guernsey
  • Average rainfall days in September: 13 days

The month with the highest number of rainy days is January (20 days).
The month with the lowest number of rainy days is July (10 days).

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).
Coldest months (with the lowest average sea temperature) are February and March (9°C).

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 shortest days is December (Average daylight: 8.3h).

  • Average sunshine in September: 6h

Months with most sunshine are May, June and July (Average sunshine: 8h).
Months with least sunshine are January, November and December (Average sunshine: 2).

Average UV index in September - Saint Peter Port, Guernsey
  • Average UV index in September: 4

Months with the highest UV index are June and July (UV index 7).
Months with the lowest UV index are January, November and December (UV index 1).