September weather forecastJuneau, AK
September
Weather in September
September marks the transition from summer to fall in Juneau. Temperatures start to drop once again, indicating upcoming changes in the weather. The warmer weather fades, and the rain starts to increase, reaching an average of 8.27" (210mm). The sea also starts to cool down, reflecting the seasonal shift. Yet, September retains ample daylight hours, meaning there is still plenty of opportunity for outdoor pursuits before winter sets in.Temperature
September's onset brings a negligible change in high-temperatures, falling from a cool 54.1°F (12.3°C) in August to a chilly 48.2°F (9°C). Juneau marks an average drop to a cold 39.7°F (4.3°C) during nighttime in September, following the high of the day.Humidity
In September, the average relative humidity in Juneau, Alaska, is 90%.Rainfall
In September, the rain falls for 21.9 days. Throughout September, 8.27" (210mm) of precipitation is accumulated. Throughout the year, in Juneau, there are 172.4 rainfall days, and 85.87" (2181mm) of precipitation is accumulated.Snowfall
In Juneau, snow does not fall in June through September.Ocean temperature
In Juneau, Alaska, the average seawater temperature in September is 50.9°F (10.5°C).Note: You can swim in 50.9°F (10.5°C) below 50°F (10°C) with proper thermal wear; failing that, the cold shock and respiratory challenges are nearly certain. A short span at 55.4°F (13°C) without it is tough.
Daylight
In September, the average length of the day in Juneau is 12h and 46min.On the first day of the month, sunrise is at 5:59 am and sunset at 7:55 pm. On the last day of September, sunrise is at 7:01 am and sunset at 6:32 pm AKDT.
Sunshine
In Juneau, the average sunshine in September is 4.9h.UV index
In Juneau, the average daily maximum UV index in September is 2. A UV Index estimate of 2, and below, represents a minimal health vulnerability from unprotected exposure to Sun's UV rays for ordinary individuals.Note: The maximum UV index, 2 during September, leads to the following recommendations:
Long-term sun exposure is typically not a concern for most. However, those with sensitive skin, infants, and children must always have protection. Considering the Sun's intensity during midday, it's wise to minimize direct exposure. For minimizing sun-related eye damage, always choose sunglasses with UVA and UVB coverage.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
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).
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).
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).
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%).
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").
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).
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").
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).
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).
Average daylight in September /
Average sunshine in September
Juneau, AK
- Average daylight in September: 12h and 48min
The month with the longest days is June (Average daylight: 18h and 12min).
The month with the shortest days is December (Average daylight: 6h and 30min).
- 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).
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).
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).
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).
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).
