Warm conditions marked September over the entire Arctic Ocean and its surrounding lands. Air temperatures at the 925 millibar level (about 2,500 feet above sea level) for the month were 2 to 4 degrees Celsius (4 to 7 degrees Fahrenheit) above the 1981 to 2010 reference period over the ocean region, reaching 4 degrees Celsius (7 degrees Fahrenheit) above average over the Beaufort Sea north of Alaska.
The surrounding Eurasian high-latitude areas experienced temperatures 1 to 2 degrees Celsius (2 to 4 degrees Fahrenheit) above the reference period average. Northern Canada and Alaska were also warm, at 1 to 4 degrees Celsius (2 to 7 degrees Fahrenheit) above average, with very warm conditions over the Yukon and eastern Alaska, which experienced temperatures 4 degrees Celsius (7 degrees Fahrenheit) above average.
Only southern Greenland experienced below-average temperatures, around 1 degree Celsius (2 degrees Fahrenheit) below the 1981 to 2010 period.
The pace of sea ice growth in late September was about average for the post-minimum period. Sea ice expanded at a rate of about 35,000 square kilometers (13,500 square miles) per day. More rapid growth is typical of October when air temperatures fall.