Arctic sea ice extent reached its annual minimum on September 13. After the minimum, extent remained largely unchanged for much of the middle of September, but increased rapidly toward the end of the month with the onset of strong autumn cooling.
Arctic sea ice extent averaged for September 2013 was 5.35 million square kilometers (2.07 million square miles). This was 1.17 million square kilometers (452,000 square miles) below the 1981 to 2010 average extent. September 2013 ice extent was 1.72 million square kilometers (664,000 square miles) higher than the previous record low for the month that occurred in 2012.