Average temperatures for September at cities, towns and parks throughout Alaska are listed below in degrees Fahrenheit and Celsius. Low temperatures at night drop to 48°F at the Southern coasts, to 35°F in the Interior and to 26°F in the Arctic region. In September the day temperatures reach 60°F in the Southern coastal areas, 53°F in the Interior regions and no more than 34°F in the Arctic region. Select a destination to see more weather parameters. You can jump to a separate table for each region of the state: Southeast, South - Central, Southwest, Interior and Far North Alaska. warning in september the weather is not the same depending on the city and regions of the country. September is not the best month to go to in Alaska. Alaska weather in September 2021. The weather in Anchorage is quite correct. Get the latest coronavirus (COVID-19) updates for the USA with current travel advice, statistics and online resources.. Below are average maximum temperatures at popular destinations in Alaska in September. The climate in Alaska in september ranges from tolerable to very bad depending on the region and city.