Jeju
South Korea
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Jeju, South Korea

A high sunrise Panorama of the Jeju Island in Jeju, South Korea
A high sunrise Panorama of the Jeju Island in Jeju, South Korea
September, the first month of the autumn, in Jeju, is still a warm month, with average temperature ranging between min 20.4°C (68.7°F) and max 25.8°C (78.4°F).

Temperature

In September, the average high-temperature marginally drops, from a warm 29.8°C (85.6°F) in August, to a still moderately hot 25.8°C (78.4°F). The average low-temperature, in September, is 20.4°C (68.7°F).

Humidity

The average relative humidity in September is 73.7%.

Rainfall

In September, the rain falls for 10.8 days. Throughout September, 221.6mm (8.7") of precipitation is accumulated. Throughout the year, in Jeju, there are 130.2 rainfall days, and 1497.7mm (59") of precipitation is accumulated.

Sea temperature

In Jeju, South Korea, in September, the average water temperature is 24.7°C (76.5°F). For individuals prone to feeling cold, swimming in 23°C (73.4°F) is still regarded as intolerable. A wetsuit is not a necessity, but sunshine, wind, and air temperature are essential factors for relishing swimming at 24.7°C (76.5°F).

Daylight

In September, the average length of the day is 12.4h.

Sunshine

In September, the average sunshine in Jeju is 5.4h.

UV index

The average daily maximum UV index in Jeju is 8. A UV Index of 8 to 10 symbolizes a very high threat to health from the exposure to the Sun's UV radiation for average individuals.
In September, the average maximum UV index of 8 translate into the following recommendations:
Take special precautions, as unprotected eyes and skin can be burned and damaged quickly. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. 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. Beware! The reflection of water and sand dramatically increases exposure to the UV rays.

What is the temperature in September in Jeju?

In Jeju, in September, the average high-temperature is 25.8°C (78.4°F), and the average low-temperature is 20.4°C (68.7°F).

What is the average humidity in September in Jeju?

The average relative humidity in September in Jeju is 73.7%.

How much does it rain in Jeju in September?

In Jeju, South Korea, during September, the rain falls for 10.8 days and regularly aggregates up to 221.6mm (8.7") of precipitation.

What is the water temperature in September in Jeju?

In Jeju, South Korea, in September, the average water temperature is 24.7°C (76.5°F). A person's cold intolerance, with sunshine, wind, and air temperature, are essential factors for enjoying swimming in 24.7°C (76.5°F) water.

What is the average length of the day in September in Jeju?

In September, the average length of the day is 12.4h.

How long on average sun shines in September in Jeju?

In September, the average sunshine in Jeju is 5.4h.

What is the UV index intensity in September in Jeju?

In Jeju, the average daily maximum UV index in September is 8. A UV Index estimate of 8 to 10 represents a very high health threat from unsafe exposure to the Sun's UV rays.
Average temperature in September - Jeju, South Korea
  • Average high temperature in September: 25.8°C

The warmest month (with the highest average high temperature) is August (29.8°C).
The month with the lowest average high temperature is January (8.3°C).

  • Average low temperature in September: 20.4°C

The month with the highest average low temperature is August (24.3°C).
The coldest month (with the lowest average low temperature) is January (3.2°C).

Average humidity in September - Jeju, South Korea
  • Average humidity in September: 73.7%

The month with the highest relative humidity is July (78.3%).
Months with the lowest relative humidity are February and March (64.9%).

Average rainfall in September - Jeju, South Korea
  • Average rainfall in September: 221.6mm

The wettest month (with the highest rainfall) is August (262.5mm).
The driest month (with the lowest rainfall) is December (47.7mm).

Average rainfall days in September - Jeju, South Korea
  • Average rainfall days in September: 10.8 days

The month with the highest number of rainy days is August (13.5 days).
The month with the lowest number of rainy days is October (7 days).

Average sea temperature in September - Jeju, South Korea
  • Average sea temperature in September: 24.7°C

The best month for swimming (with the highest average sea temperature) is August (26.2°C).
The coldest month (with the lowest average sea temperature) is March (13.3°C).

Average daylight in September / Average sunshine in September - Jeju, South Korea
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 14.4h).
The month with shortest days is December (Average daylight: 10h).

  • Average sunshine in September: 5.4h

The month with most sunshine is May (Average sunshine: 6.8h).
The month with least sunshine is January (Average sunshine: 2.3h).

Average UV index in September - Jeju, South Korea
  • Average UV index in September: 8

The month with the highest UV index is July (UV index 11).
Months with the lowest UV index are January and December (UV index 3).