The National Snow and Ice Data Center (NSIDC) is part of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder. NSIDC scientists provide Arctic Sea Ice News & Analysis content, with partial support from NASA.
Arctic sea ice cover appears to have reached its minimum extent on September 11, 2015. Sea ice extent on that day was measured at 4.41 million square kilometers (1.70 million square miles). It was the fourth lowest extent recorded since satellites began measuring sea ice in 1979.
Please note that the Arctic sea ice extent number is preliminary—changing winds could still push the ice extent lower. NSIDC will issue a formal announcement at the beginning of October with full analysis of the possible causes behind this year's ice conditions, particularly interesting aspects of the melt season, the set up going into the winter growth season ahead, and graphics comparing this year to the long-term record.
See the full announcement at NSIDC's Arctic Sea Ice News and Analysis page.