Anchorage Weather in September

September's weather cools enough to bring the first fall frosts to Anchorage, Alaska. Most years though, don't get snow this early.

This page gives detailed information on typical September temperature, precipitation, sun, humidity, wind and storms for Anchorage. The numbers here are historical averages based on climate data gathered at the Ted Stevens Anchorage International Airport, located a few miles from downtown Anchorage.

Temperature Weather iconTemperature

56 °F September average high 13 °C
43 °F September average low 6 °C
26 days 50 °F max. or more (10 °C)
9 days 40 °F min. or less (4 °C)

Usually every day in September warms to over 40 degrees Fahrenheit (4 degrees Celsius) in Anchorage. The city averages 8 days this month when the thermometer reaches into the 60s °F (over 16 °C). Temperatures above 70 °F (21 °C) occur rarely here during September.

The temperature dips to freezing or below on an average of 3 nights. But September does not normally get as cold as 20 °F (-8 °C).

Rainy Weather iconPrecipitation

3.1 in total precipitation 79 mm
15 days of rain or snowfall

Half the time, Anchorage receives 1.9 to 3.9 inches (48 to 99 mm) of rainfall in September. One in four years has drier weather, while another one in four is wetter. Every few years, some of September's precipitation falls as snow.

Sunny Weather iconSun

38 % sunshine
4 days clear skies

The sun's rays reach the ground in Anchorage during 38 percent of daylight hours on average in September, for a total of 146 hours in the month. Typically on 4 days this month the sky is mainly clear, with at most 30 percent cloud cover.

Sunlight in September at Anchorage lasts for 12 hours and 50 minutes a day on average. The longest day of the month is the 1st with 14 hours and 12 minutes of daylight. By the end of the month, the days have shortened to 11:28 from sunrise to sunset. These durations can vary by a minute or three from year to year.

Humid Weather iconHumidity

76 % September average humidity

The relative humidity in Anchorage during September usually peaks at 84 percent in the morning then drops to 64 percent by mid afternoon.

Local Time12 am3 am6 am9 am12 pm3 pm6 pm9 pm
Humidity % 80 82 84 81 70 64 68 78

Windy Weather iconWind

6.7 mph September wind speed average 10.8 kph

September is a little less windy than most other months in Anchorage.

Stormy Weather iconStorms

2 days rainfall of 0.5 inches (13 mm) or more
0 days with thunderstorms in September

About once a decade, Anchorage has a thunderstorm during September. And a heavy snowstorm is equally as common this month.


The weather data here are long-term averages provided by the US National Centers for Environmental Information (NCEI). Temperature and precipitation are 1991-2020 normals while humidity and thunderstorms are 1961-1990 normals.

Anchorage Weather
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