Ice-on date arrives days after the new year
Air temperatures below the freezing mark throughout the last week, combined with cold water helped Lake Mendota officially freeze on Sunday, January 3rd, 2021, as declared by the Wisconsin State Climatology Office. Lake Mendota, the largest lake in the Yahara Watershed, froze 27 days shy of January 30th – which is the latest date that ice-on has ever been declared (1/30/1932).
The Wisconsin State Climatology Office requires ice to hold for a period of 24 hours before a lake can officially be declared frozen over. The January 3rd freeze date is nine days before last year’s freeze date of January 12th. The median freeze date for Lake Mendota is December 20th.

We have a winner!
Clean Lakes Alliance once again held its annual Mendota Freeze Contest in the winter of 2020-2021. The contest asks people to make a guess about when the lake would officially freeze. Of the more than 1,800 people to enter the contest, over 50 guessed Lake Mendota would freeze on January 3rd.
Randomly selected from those to guess the correct date was Wayne J. Hanson of Poynette. He will receive a $1,000 gift card courtesy of Lands’ End as the grand prize. Hanson says he will likely use his winnings to buy a Lands’ End blanket or two for his wife, and an ice fishing jacket for himself. This was the first time Hanson entered the Mendota Freeze Contest, which he saw advertised on Facebook. He said his January 3rd date was just a lucky guess!

All Madison area lakes are officially frozen
The other shallower lakes in the Yahara chain typically freeze earlier than Lake Mendota, and are determined by different methods and organizations. Below is the list of “ice on” dates and the correlating organization that makes the call.
Lake and freeze date
Lake Mendota – Jan. 3, 2021
Lake Monona – Dec. 29, 2020
Lake Wingra – Dec. 6 & 13, 2020
Lake Kegonsa – Dec. 25, 2020
Lake Waubesa – Dec. 18 & 25, 2020
“Ice on” determination
Wisconsin State Climatology Office
Wisconsin State Climatology Office
Wisconsin State Climatology Office
Friends of Lake Kegonsa Society
Christenson family – Christy’s Landing
Stay safe!
Though the lakes look solid, don’t be misled – ice may still be thin. The Wisconsin Department of Natural Resources recommends waiting for at least four inches of ice to develop before heading out to ice fish on our lakes. If you are venturing out on the lake, always let someone know where you are going or take a friend with you!
Read more about our annual Mendota Freeze Contest.