10th annual Mendota Freeze Contest begins


Clean Lakes Alliance kicks off annual Mendota Freeze Contest

On Wednesday, December 1st, 2021, Clean Lakes Alliance kicked off its 10th annual Mendota Freeze Contest. This year, Greater Madison experienced near-normal November temperatures. As of the first of the month, Lake Mendota, and the other four Greater Madison lakes, remained completely open. Despite this week’s mild temperatures, 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.

mendota freeze contest

“When the lakes freeze, they become our largest parks,” said 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.”

Making it official

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 20 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 year, a warm December kept Lake Mendota open well past its median freeze date and even through the end of 2020. The largest lake in the Yahara Watershed officially froze over on January 3rd, 2021. The early-January ice-on day was 27 days shy of the latest freeze date on record – January 30, 1932.

The Wisconsin State Climatology Office declared Lake Mendota “open” again on March 20, 2021. The 77-day freeze duration was well shy of the median freeze duration of 104 days. 


Mendota Freeze Contest  

On December 1st at 7:00 a.m., Clean Lakes Alliance will kick off its 10th 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.

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
  • Freeze Date LAST Winter:     January 3, 2021
  • Median Freeze Date:              December 20

View a complete list of historical freeze dates for Lake Mendota.

Learn more about Clean Lakes Alliance’s annual Mendota Freeze Contest.

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