Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average sea temperature in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
With the onset of September, Unalaska's average high-temperature clocks in at a still fresh 50°F (10°C), showing a minor fluctuation from the previous month. During the nights of September, Unalaska records an average temperature of 47.1°F (8.4°C), a minor drop from daytime peaks.Humidity
In September, the average relative humidity is 87%.Rainfall
In September, the rain falls for 19.8 days. Throughout September, 2.72" (69mm) of precipitation is accumulated. Throughout the year, there are 198.8 rainfall days, and 33.78" (858mm) of precipitation is accumulated.Snowfall
In Unalaska, snow does not fall in June through September.Ocean temperature
In Unalaska, in September, the average water temperature is 48.6°F (9.2°C).Note: Swimming at temperatures less than 50°F (10°C) in 48.6°F (9.2°C) is feasible with the right swimsuit; if not, expect cold shock and breathlessness. A quick swim at 55.4°F (13°C) without adequate warmth can be discomforting.
Daylight
In September, the average length of the day is 12h and 40min.On the first day of the month, sunrise is at 8:16 am and sunset at 9:55 pm. On the last day of September, sunrise is at 9:08 am and sunset at 8:43 pm AKDT.
Sunshine
In Unalaska, the average sunshine in September is 4.7h.UV index
In September, the average daily maximum UV index is 2. A UV Index value of 2, and less, symbolizes a minimal health vulnerability from exposure to the Sun's UV radiation for the average person.Note: The UV index of 2 in September translates into these instructions:
While sun exposure does not greatly affect most, individuals with fair skin, babies, and children always need vigilant safeguarding. Protect yourself from the midday Sun's peak UV radiation by minimizing exposure. Combat UV radiation's detrimental effects with sun-safe clothing and UV-blocking eyewear.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are September temperatures?
What is the average humidity in September in Unalaska?
How much does it rain in September?
When it does not snow in Unalaska?
Does it snow in September?
How cold is the water in September?
How many hours of daylight does Unalaska have in September?
When are sunrise and sunset in September?
How many hours of sunshine does Unalaska have in September?
What is the UV index intensity in September in Unalaska?
Average temperature in September
Unalaska, AK
- Average high temperature in September: 50°F
The warmest month (with the highest average high temperature) is August (53.2°F).
The month with the lowest average high temperature is March (34.7°F).
- Average low temperature in September: 47.1°F
The month with the highest average low temperature is August (49.6°F).
The coldest month (with the lowest average low temperature) is March (30.7°F).
Average pressure in September
Unalaska, AK
- Average pressure in September: 29.79"Hg
The month with the highest atmospheric pressure is July (29.98"Hg).
The month with the lowest atmospheric pressure is January (29.5"Hg).
Average wind speed in September
Unalaska, AK
- Average wind speed in September: 12.9mph
The windiest months (with the highest average wind speed) are November and December (16.5mph).
The calmest month (with the lowest average wind speed) is July (9.1mph).
Average humidity in September
Unalaska, AK
- Average humidity in September: 87%
The month with the highest relative humidity is July (91%).
The months with the lowest relative humidity are November and December (80%).
Average rainfall in September
Unalaska, AK
- Average rainfall in September: 2.72"
The wettest month (with the highest rainfall) is December (4.21").
The driest month (with the least rainfall) is July (1.85").
Average rainfall days in September
Unalaska, AK
- Average rainfall days in September: 19.8 days
The month with the highest number of rainy days is October (21.8 days).
The month with the least rainy days is February (11.1 days).
Average snowfall in September
Unalaska, AK
- Average snowfall in September: 0"
The month with the highest snowfall is January (6.97").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Unalaska, AK
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (14.2 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average sea temperature in September
Unalaska, AK
- Average sea temperature in September: 48.5°F
The best month for swimming (with the highest average sea temperature) is August (50.1°F).
The coldest month (with the lowest average sea temperature) is February (38.8°F).
Average daylight in September /
Average sunshine in September
Unalaska, AK
- Average daylight in September: 12h and 4min
The month with the longest days is June (Average daylight: 17h and 0min).
The month with the shortest days is December (Average daylight: 7h and 30min).
- Average sunshine in September: 4h and 4min
The month with the most sunshine is June (Average sunshine: 5h and 48min).
The month with the least sunshine is December (Average sunshine: 2h and 0min).
Average sunshine days in September
Unalaska, AK
- Average sunshine days in September: 6.9 days
The month with the most sunshine days is August (9.7 days).
The month with the least sunshine days is April (3.8 days).
Average UV index in September
Unalaska, AK
- Average UV index in September: 2
The months with the highest UV index are July and August (UV index 3).
The months with the lowest UV index are February, March, April and November (UV index 1).
Average cloud cover in September
Unalaska, AK
- Average cloud cover in September: 66
The month with the most cloud cover is July (Cloud cover 74).
The months with the least cloud cover are September and October (Cloud cover 66).
Average visibility in September
Unalaska, AK
- Average visibility in September: 6mi
The months with the highest visibility are May, June, August, September, October and November (6mi).
The months with the lowest visibility are January, February, March, April, July and December (5mi).
Unalaska, Alaska, USA
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