Saint Helier
Jersey
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Saint Helier, Jersey

A shot of the Elizabeth Castle found on Tidal Island in Saint Helier Parish, Jersey
A shot of the Elizabeth Castle found on Tidal Island in Saint Helier Parish, Jersey
September, the first month of the autumn, in Saint Helier, is still a comfortable month, with temperature in the range of an average low of 12.9°C (55.2°F) and an average high of 19.3°C (66.7°F).

Temperature

In Saint Helier, Jersey, the average high-temperature is practically the same as in August - an enjoyable 19.3°C (66.7°F). In September, the average low-temperature is 12.9°C (55.2°F).

Rainfall

In September, the rain falls for 13.3 days. Throughout September, 70.3mm (2.8") of precipitation is accumulated. In Saint Helier, during the entire year, the rain falls for 176.4 days and collects up to 853.3mm (33.6") of precipitation.

Sea temperature

In September, the average sea 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).

Daylight

The average length of the day in Saint Helier is 12.6h.

Sunshine

In September, the average sunshine is 6h.

UV index

The average daily maximum UV index in Saint Helier is 4. A UV Index estimate of 3 to 5 represents a moderate health risk from unprotected exposure to the Sun's UV rays for average individuals.
In September, the average maximum UV index of 4 translate into the following recommendations:
Take precautions - Protection against sun damage is advised. 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.

What is the temperature in September in Saint Helier?

In September, in Saint Helier, Jersey, the average high-temperature is 19.3°C (66.7°F), and the average low-temperature is 12.9°C (55.2°F).

How much does it rain in Saint Helier in September?

In Saint Helier, during September, the rain falls for 13.3 days and regularly aggregates up to 70.3mm (2.8") of precipitation.

What is the sea temperature in September in Saint Helier?

In September, the average sea temperature in Saint Helier is 16°C (60.8°F). 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).

How many hours of daylight does Saint Helier have in September?

In September, the average length of the day is 12.6h.

How many hours of sunshine does Saint Helier have in September?

In September, the average sunshine is 6h.

What is the UV index reading in September in Saint Helier?

The average daily maximum UV index in September in Saint Helier is 4. A UV Index estimate of 3 to 5 represents a medium health risk from unsafe exposure to the Sun's UV rays.
Average temperature in September - Saint Helier, Jersey
  • Average high temperature in September: 19.3°C

The warmest month (with the highest average high temperature) is August (21.2°C).
The month with the lowest average high temperature is January (9.5°C).

  • Average low temperature in September: 12.9°C

The month with the highest average low temperature is August (14.4°C).
The coldest month (with the lowest average low temperature) is February (4°C).

Average rainfall in September - Saint Helier, Jersey
  • Average rainfall in September: 70.3mm

The wettest month (with the highest rainfall) is December (110.5mm).
The driest month (with the lowest rainfall) is July (37mm).

Average rainfall days in September - Saint Helier, Jersey
  • Average rainfall days in September: 13.3 days

The month with the highest number of rainy days is December (19.5 days).
The month with the lowest number of rainy days is July (9.9 days).

Average sea temperature in September - Saint Helier, Jersey
  • 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 Helier, Jersey
  • 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, July and August (Average sunshine: 8h).
Months with least sunshine are January and December (Average sunshine: 2).

Average UV index in September - Saint Helier, Jersey
  • 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).