Ice breakup dates of Chequamegon Bay, Lake Superior from 1911 to 2021 were compiled by Lori Evrard (USGS, GLSC, Lake Superior Biological Station, Ashland, WI). Ice breakup date is the day in spring when winter ice cover substantially leaves a water body. Local residents deem "ice breakup" as when the ice moves northeast of a line straight across Chequamegon Bay out from Ellis Avenue (State highway 13). Another way ice breakup was determined has been if you could drive a boat from the outlet of Fish Creek to Houghton Point. The ice may move back and forth over that line but the ice is breaking up, moving and melting from that date on. Ellis Avenue ends on a bluff (46.5925 degrees North, 90.8827 degrees West) that provides a clear view of Chequamegon Bay from Fish Creek to Houghton Point. Mrs. C. J. Hoskings recorded the dates from 1911 to 1980. Mr. LeRoy C. Margenau recorded the dates from 1981 to 1991. The Ashland Marina recorded the dates from 1992-1999 and 2001. Lori Evrard (USGS) recorded dates after 1999 except 2001. USGS converted each date to a consecutive day of the year value. The date of ice breakup will be updated annually to append that year's date.