Juneau
Alaska, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Juneau, AK

Blooming fireweed in Juneau, Alaska, with snowy mountain peaks in the distance
Blooming fireweed in Juneau, Alaska, with snowy mountain peaks in the distance
September, the first month of the autumn, in Juneau, is also a moderate month, with average temperature fluctuating between 44.4°F (6.9°C) and 55.8°F (13.2°C).

Temperature

In September, the average high-temperature slightly decreases, from a comfortable 62.8°F (17.1°C) in August, to a mild 55.8°F (13.2°C). The average low-temperature, in Juneau, is 44.4°F (6.9°C).

Humidity

September is the most humid month in Juneau, with an average relative humidity of 87.9%.

Rainfall

The month with the most rainfall in Juneau is September when the rain falls for 22.4 days and typically aggregates up to 8.6" (219.5mm) of precipitation.

Snowfall

In Juneau, it doesn't snow. In October, it regularly snows. Throughout the year, 86.7" (2202mm) of snow is accumulated.

Ocean temperature

In Juneau, Alaska, the average seawater temperature in September is 50.9°F (10.5°C). Swimming in 50.9°F (10.5°C) is considered life-threatening. Even a few minutes in 55.4°F (13°C) water is uncomfortable, and swimming below 50°F (10°C) may cause total loss of breathing control and cold shock, depending on a person's physique.

Daylight

In Juneau, the average length of the day is 12.8h.

Sunshine

In September, the average sunshine in Juneau is 3.7h.

UV index

In Juneau, the average daily maximum UV index is 3. A UV Index reading of 3 to 5 represents a medium health hazard from the exposure to the Sun's UV rays for the average person.
The daily maximum UV index of 3 in September interpret into the following advice:
Take precautions - Protection against sunburn is recommended. 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 Juneau?

In September, in Juneau, Alaska, the average high-temperature is 55.8°F (13.2°C), and the average low-temperature is 44.4°F (6.9°C).

What is the most humid month in Juneau?

The most humid month is September, with an average relative humidity of 87.9%.

What is the average humidity in September in Juneau?

The average relative humidity in September is 87.9%.

How much does it rain in Juneau in September?

In Juneau, Alaska, during September, the rain falls for 22.4 days and regularly aggregates up to 8.6" (219.5mm) of precipitation.

What is the rainiest month in Juneau?

The month with the most rainfall in Juneau, Alaska, is September when the rain falls for 22.4 days and typically aggregates up to 8.6" (219.5mm) of precipitation.

Does it snow in Juneau in September?

In Juneau, Alaska, in September, it doesn't snow. In October, it regularly snows.

How cold is the water in September in Juneau?

In Juneau, Alaska, in September, the average water temperature is 50.9°F (10.5°C). Swimming in 50.9°F (10.5°C) is considered life-threatening. Even a few minutes in 55.4°F (13°C) water is uncomfortable, and swimming below 50°F (10°C) may cause total loss of breathing control and cold shock, depending on a person's physique.

How many hours of daylight does Juneau have in September?

In September, the average length of the day in Juneau, Alaska, is 12.8h.

How many hours of sunshine does Juneau have in September?

The average sunshine in September is 3.7h.

What is the UV index reading in September in Juneau?

The average daily maximum UV index in September in Juneau, Alaska, is 3. A UV Index of 3 to 5 symbolizes a moderate vulnerability from unprotected exposure to the UV radiation.
Average temperature in September - Juneau, AK
  • Average high temperature in September: 13.2°C

The warmest month (with the highest average high temperature) is July (17.7°C).
The month with the lowest average high temperature is January (0.4°C).

  • Average low temperature in September: 6.9°C

The month with the highest average low temperature is July (10°C).
The coldest month (with the lowest average low temperature) is January (-4.6°C).

Average humidity in September - Juneau, AK
  • Average humidity in September: 87.9%

The month with the highest relative humidity is September (87.9%).
The month with the lowest relative humidity is May (76.3%).

Average rainfall in September - Juneau, AK
  • Average rainfall in September: 219.5mm

The wettest month (with the highest rainfall) is September (219.5mm).
The driest month (with the lowest rainfall) is April (74.7mm).

Average rainfall days in September - Juneau, AK
  • Average rainfall days in September: 22.4 days

The month with the highest number of rainy days is October (23.9 days).
The month with the lowest number of rainy days is June (15.8 days).

Average snowfall in September - Juneau, AK
  • Average snowfall in September: 0mm

The month with the highest snowfall is January (703.6mm).
Months with the lowest snowfall are May, June, July, August and September (0mm).

Average snowfall days in September - Juneau, AK
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (10.6 days).
Months with the lowest number of snowfall days are May, June, July, August and September (0 days).

Average sea temperature in September - Juneau, AK
  • Average sea temperature in September: 10.5°C

The best month for swimming (with the highest average sea temperature) is August (11.9°C).
The coldest month (with the lowest average sea temperature) is March (4.7°C).

Average daylight in September / Average sunshine in September - Juneau, AK
  • Average daylight in September: 12.8h

The month with the longest days is June (Average daylight: 18.2h).
The month with shortest days is December (Average daylight: 6.5h).

  • Average sunshine in September: 3.7h

The month with most sunshine is May (Average sunshine: 7.5h).
The month with least sunshine is December (Average sunshine: 1.3h).

Average UV index in September - Juneau, AK
  • Average UV index in September: 3

Months with the highest UV index are June and July (UV index 5).
Months with the lowest UV index are January, November and December (UV index 0).