We are heading into the time of year when sub zero temperatures occur somewhere in Alaska every day. In 2013 the first occurrence of a subzero day in the databases that NCDC maintains was on October 10th. A couple of stations nearly reached zero the other day as Richard noted but it doesn't appear to have happened yet in Alaska. The following chart shows the statewide average high and low temperature (red colums) and the daily extremes (gray shaded area) between January 1, 2012, and September 24, 2013. It appears that June 18th was the warmest day in Alaska in 2013.
Note: You can zoom into the chart to see much shorter time periods. Click the Reset Zoom button to go back to the original view.