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

Weather in September

September, the first month of the autumn, in Juneau, is also a frosty month, with average temperature fluctuating between 39.7°F (4.3°C) and 48.2°F (9°C).

Temperature

In Juneau, the average high-temperature in September marginally drops, from a fresh 54.1°F (12.3°C) in August, to a chilly 48.2°F (9°C). The average low-temperature, in September, is 39.7°F (4.3°C).

Humidity

In Juneau, the average relative humidity in September is 90%.

Rainfall

In September, in Juneau, the rain falls for 21.9 days. Throughout September, 8.27" (210mm) of precipitation is accumulated. In Juneau, during the entire year, the rain falls for 172.4 days and collects up to 85.87" (2181mm) of precipitation.

Snowfall

In Juneau snow does not fall in June through September.

Ocean temperature

In Juneau, Alaska, the average seawater temperature is 50.9°F (10.5°C).
Note: At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.

Daylight

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

Sunshine

In Juneau, the average sunshine in September is 4.9h.

UV index

In September, the average daily maximum UV index is 2. A UV Index estimate of 2, and below, represents a low health risk from the exposure to the Sun's UV rays for the average person.
Note: In September, the average maximum UV index of 2 translate into the following recommendations:
For the majority, extended sun exposure is not of great concern. Infants and people with sensitive skin must always be protected. 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.
[Resources]

FAQ

What is the temperature in September in Juneau?

The average high-temperature, in September, in Juneau, is 48.2°F (9°C), while the average low-temperature is 39.7°F (4.3°C).

What is the average humidity in September in Juneau?

In September, the average relative humidity is 90%.

How many days does it rain in September in Juneau?

In Juneau, Alaska, in September, it is raining for 21.9 days, with typically 8.27" (210mm) of accumulated precipitation.

Does it snow in Juneau in September?

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

When it does not snow in Juneau?

June through September are months without snowfall.

How cold is the water in September in Juneau?

In Juneau, 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.

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

The average length of the day in September is 12.8h.

How many hours of sunshine does Juneau have in September?

In Juneau, Alaska, the average sunshine in September is 4.9h.

What is the UV index intensity in September in Juneau?

The average daily maximum UV index in September in Juneau is 2. A UV Index of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to the UV radiation.

Average temperature in September
Juneau, AK

Average temperature in September - Juneau, AK
  • Average high temperature in September: 9°C

The warmest month (with the highest average high temperature) is July (13.2°C).
Months with the lowest average high temperature are January and December (-3.5°C).

  • Average low temperature in September: 4.3°C

The month with the highest average low temperature is July (7.3°C).
The coldest month (with the lowest average low temperature) is February (-8.3°C).

[Resources]

Average pressure in September
Juneau, AK

Average pressure in September - Juneau, AK
  • Average pressure in September: 1012.1mbar

The month with the highest atmospheric pressure is July (1016.8mbar).
The month with the lowest atmospheric pressure is November (1009.1mbar).

[Resources]

Average wind speed in September
Juneau, AK

Average wind speed in September - Juneau, AK
  • Average wind speed in September: 8.3km/h

The windiest month (with the highest average wind speed) is January (11.1km/h).
The calmest month (with the lowest average wind speed) is June (5.9km/h).

[Resources]

Average humidity in September
Juneau, AK

Average humidity in September - Juneau, AK
  • Average humidity in September: 90%

The month with the highest relative humidity is January (92%).
The month with the lowest relative humidity is May (86%).

[Resources]

Average rainfall in September
Juneau, AK

Average rainfall in September - Juneau, AK
  • Average rainfall in September: 210mm

The wettest month (with the highest rainfall) is October (251mm).
The driest month (with the least rainfall) is May (105mm).

[Resources]

Average rainfall days in September
Juneau, AK

Average rainfall days in September - Juneau, AK
  • Average rainfall days in September: 21.9 days

The month with the highest number of rainy days is September (21.9 days).
The month with the least rainy days is February (4.8 days).

[Resources]

Average snowfall in September
Juneau, AK

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

The month with the highest snowfall is December (1595mm).
Months with the least snowfall are June, July, August and September (0mm).

[Resources]

Average snowfall days in September
Juneau, AK

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 (21.9 days).
Months with the least snowfall days are June, July, August and September (0 days).

[Resources]

Average sea temperature in September
Juneau, AK

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).

[Resources]

Average daylight in September /
Average sunshine in September
Juneau, AK

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 the shortest days is December (Average daylight: 6.5h).

  • Average sunshine in September: 4.9h

The month with the most sunshine is June (Average sunshine: 6.4h).
The month with the least sunshine is November (Average sunshine: 2.6h).

[Resources]

Average sunshine days in September
Juneau, AK

Average sunshine days in September - Juneau, AK
  • Average sunshine days in September: 7.5 days

The month with the most sunshine days is May (10 days).
The month with the least sunshine days is November (6.1 days).

[Resources]

Average UV index in September
Juneau, AK

Average UV index in September - Juneau, AK
  • Average UV index in September: 2

Months with the highest UV index are May and July (UV index 3).
Months with the lowest UV index are January, April, October, November and December (UV index 1).

[Resources]

Average cloud cover in September
Juneau, AK

Average cloud cover in September - Juneau, AK
  • Average cloud cover in September: 67

Months with the most cloud cover are January and November (Cloud cover 72).
The month with the least cloud cover is May (Cloud cover 61).

[Resources]

Average visibility in September
Juneau, AK

Average visibility in September - Juneau, AK
  • Average visibility in September: 7km

Months with the highest visibility are February, March, May, June, July, August, September, October and November (7km).
Months with the lowest visibility are January, April and December (6km).

[Resources]