October is the first month of the winter freeze in the Arctic Ocean. Here’s how the ice cover for Oct 2018 compares with previous Octobers.
Sea ice extent for October 2018 fell below the long-term linear trend line. The linear rate of sea ice decline for October is 79,000 square kilometers (31,000 square miles) per year, or 9.5 percent per decade relative to the 1981 to 2010 average.
https://nsidc.org/arcticseaicenews/files/2018/11/Figure3-350×270.png
https://nsidc.org/arcticseaicenews/