The Wisconsin State Climatology Office, housed at the University of Wisconsin-Madison, monitors and reports on the ice coverage of Madison lakes.
The office keeps a database of the ice-over and ice-out dates for three Madison-area lakes: Mendota, Monona and Wingra. These records extend back to the winters of 1855-1856 for Mendota and Monona. The record of annual ice cover of Wingra is spotty, but consistent starting in the winter of 1982-83. Due to the long record based on visual observations, it is no surprise that the rules of opening and closing have been handed down by oral tradition.
Ice coverage data for lakes Monona and Wingra are based on a general “50 percent covered” rule. The size and irregular shoreline of Lake Mendota make it challenging to observe, and so ice coverage is based on “whether one can row a boat between Picnic Point and Maple Bluff.” The lore is that in the early era, this rule was developed based on observers’ ability to bring a case of beer in a rowboat to friends on the other shore.
This year, without a rowboat, the observers determined that both Lake Mendota and Lake Monona froze over on Monday, Jan. 15. The recent cold air outbreak helped in covering the lakes with ice. Lake Wingra has frozen and thawed multiple times already this winter but has been frozen over consistently since Jan. 5.
This winter’s freeze-over date for lakes Mendota and Monona is the third-latest on record. Mendota froze over on Jan. 20, 2007, and Jan. 30, 1932. Monona froze over on Jan. 18, 2007, and January 30, 1932.
With the forecast of warmer weather this week, it will be interesting to see whether the lakes remain iced over.
And a big thank you to Ed Hopkins, Lyle Anderson and David Liebl, who annually brave our winter weather to assess ice conditions on the lakes.
Steve Ackerman and Jonathan Martin, professors in the UW-Madison department of atmospheric and oceanic sciences, are guests on WHA radio (970 AM) at 11:45 a.m. the last Monday of each month. Send them your questions at stevea@ssec.wisc.edu or jemarti1@wisc.edu.
