September weather forecast
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 still a chilly month, with temperature in the range of an average high of 48.2°F (9°C) and an average low of 39.7°F (4.3°C).

Temperature

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

Humidity

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

Rainfall

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

Snowfall

June through September are months without snowfall.

Ocean temperature

In Juneau, Alaska, in September, the average water 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 in September is 12h and 46min.
On the first day of September, sunrise is at 5:57 am and sunset at 7:57 pm. On the last day of the month, sunrise is at 7:00 am and sunset at 6:34 pm AKDT.

Sunshine

The average sunshine in September is 4.9h.

UV index

The average daily maximum UV index in September in Juneau is 2. A UV Index of 2, and less, symbolizes a minimal health hazard from exposure to the Sun's UV rays for the ordinary person.
Note: The daily maximum UV index of 2 in September interpret into the following advice:
Extended sun exposure is not an issue for the majority. Children, infants, and fair-skinned individuals always need to 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.
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FAQ

What is the average humidity in September in Juneau?

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

How many days does it rain in September in Juneau?

In September, in Juneau, Alaska, the rain falls for 21.9 days. Throughout September, 8.27" (210mm) of precipitation is accumulated.

When it does not snow in Juneau?

June through September are months without snowfall.

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, the average seawater temperature in September is 50.9°F (10.5°C). Swimming in 50.9°F (10.5°C) is considered dangerous. Unprotected immersion in temperatures below 50°F (10°C) causes quickly maximum intensity cold shock with hyperventilation.

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

The average day length in September is 12h and 46min.

When is the sunrise / sunset in September in Juneau?

On the first day of September, sunrise is at 5:57 am and sunset at 7:57 pm. On the last day of the month, sunrise is at 7:00 am and sunset at 6:34 pm AKDT.

How long on average sun shines in September in Juneau?

The average sunshine duration 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, Alaska, is 2. A UV Index of 2, and less, symbolizes a minimal health vulnerability from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Juneau, AK

Average temperature in September - Juneau, AK
  • Average high temperature in September: 48.2°F

The warmest month (with the highest average high temperature) is July (55.8°F).
The months with the lowest average high temperature are January and December (25.7°F).

  • Average low temperature in September: 39.7°F

The month with the highest average low temperature is July (45.1°F).
The coldest month (with the lowest average low temperature) is February (17.1°F).

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Average pressure in September
Juneau, AK

Average pressure in September - Juneau, AK
  • Average pressure in September: 29.89"Hg

The month with the highest atmospheric pressure is July (30.03"Hg).
The month with the lowest atmospheric pressure is November (29.8"Hg).

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Average wind speed in September
Juneau, AK

Average wind speed in September - Juneau, AK
  • Average wind speed in September: 5.2mph

The windiest month (with the highest average wind speed) is January (6.9mph).
The calmest months (with the lowest average wind speed) are June and July (3.7mph).

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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%).

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Average rainfall in September
Juneau, AK

Average rainfall in September - Juneau, AK
  • Average rainfall in September: 8.27"

The wettest month (with the highest rainfall) is October (9.88").
The driest month (with the least rainfall) is May (4.13").

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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).

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Average snowfall in September
Juneau, AK

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

The month with the highest snowfall is December (62.8").
The months with the least snowfall are June, July, August and September (0").

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

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Average sea temperature in September
Juneau, AK

Average sea temperature in September - Juneau, AK
  • Average sea temperature in September: 50.9°F

The best month for swimming (with the highest average sea temperature) is August (53.5°F).
The coldest month (with the lowest average sea temperature) is March (40.3°F).

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

Average daylight in September / Average sunshine in September - Juneau, AK
  • Average daylight in September: 12h and 46min

The month with the longest days is June (Average daylight: 18h and 9min).
The month with the shortest days is December (Average daylight: 6h and 31min).

  • Average sunshine in September: 4h and 54min

The month with the most sunshine is June (Average sunshine: 6h and 24min).
The month with the least sunshine is November (Average sunshine: 2h and 36min).

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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).

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Average UV index in September
Juneau, AK

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

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

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Average cloud cover in September
Juneau, AK

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

The 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).

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Average visibility in September
Juneau, AK

Average visibility in September - Juneau, AK
  • Average visibility in September: 4mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (4mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (4mi).

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