Clean Lakes Alliance: When will Lake Mendota freeze? 

Clean Lakes Alliance to kick off annual Mendota Freeze Contest

MADISON, Wis., December 1, 2024 – Despite a few cold snaps, temperatures throughout the month of November averaged above normal. The mild temperatures mean that as of December 1st, Lake Mendota, and the other four Greater Madison lakes, remained completely open. No matter what the temperature is at the end of November and the start of December, more than 165 years of data show the median freeze date for Lake Mendota is only a little under three weeks away on December 20th.

            “When the lakes freeze, they become our largest parks,” exclaimed Clean Lakes Alliance Founder and Executive Director James Tye. “While a lot of people may only think of using the lakes in the summer, they are great for winter activities too – which really makes the lakes the center of our community all year long.”

According to the Wisconsin State Climatology Office, which makes the official ruling on ice cover on the lakes, Lake Mendota has ALWAYS frozen – even if only for a short duration. In fact, just 22 years ago (winter of 2001-02), the lake was officially frozen for only 21 days. That three-week ice-on period is much shorter than the record 161 days, set in the winter of 1880-81.

Last winter, Lake Mendota officially freeze on January 15, 2024. Lake Mendota, the largest lake in the Yahara Watershed, froze a full 26 days after December 20th, which is the median ice-on date for the largest lake in the Yahara River Watershed. The January 15th freeze is the 3rdlatest freeze date since monitoring began over 170 years ago. The latest date ice-on has been declared is January 30th, and that took place in 1932.

Mendota Freeze Contest   

On December 1st, Clean Lakes Alliance will kick off its 14th annual Mendota Freeze Contest. Calling on weather watchers and ice experts of all ages, the contest asks people to guess the official ice-on date for Lake Mendota. All entries to correctly guess the date will be entered to win a $1,000 gift card, courtesy of Lands’ End. To enter a guess and view contest rules, visit mendotafreeze.org

Freezing Facts

Here are some historical facts to help Mendota Freeze contestants make a more accurate guess:

Earliest Freeze Date:              November 23, 1880

Latest Freeze Date:                January 30, 1932

Median Freeze Date:              December 20

Fore a complete list of historical freeze dates for Lake Mendota, visit: aos.wisc.edu/~sco/lakes/Mendota-ice.html