Lake Mendota officially frozen over as of Christmas Day

MADISON, Wis. — Madison’s largest lake officially froze over on Christmas Day thanks in large part to a recent stretch of sustained sub-freezing temperatures.

Last week’s extremely cold temperatures helped set the stage for the big freeze just five days after the lake’s median ice-on date, which is December 20.

To meet the Wisconsin State Climatology Office’s criteria, the ice must hold for 24 hours before a lake can be declared frozen over. Lake Mendota froze over on Jan. 7, 2022, during last year’s winter season, roughly two weeks later than this year.

The record for Lake Mendota’s latest freeze date is January 30, which was set in 1932.

Despite the surface now being covered, venturing out onto the ice always comes with risks. With temperatures expected to stretch well into the 40s multiple days later this week, there’s a chance parts of the lake could thaw, making trips onto the ice even more dangerous for the time being.

“At about four inches of ice thickness, you can go out there with reasonable certainty that it’s okay, but you should always check on ice conditions,” said James Tye, the Clean Lakes Alliance’s executive director. “With it warming up this week, we do expect to have a little bit of thaw, so I think the lakes will be a little bit unstable the next couple of days.”

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Officials with the Wisconsin Department of Natural Resources recommend waiting until there’s at least four inches of ice built up before heading out to ice fish, ice skate or participate in any other winter activities on the frozen water.

Regardless of the ice’s thickness, officials recommend letting someone know where you’re going, or better yet, taking someone with you.

Lakes Monona and Wingra both froze over earlier this month, according to state data.

Each year, the Clean Lakes Alliance holds a contest to guess the lake’s ice-on date; of the nearly 1,600 people who entered this year, 33 of them guessed correctly. The randomly selected winner will receive a $1,000 gift card from Lands’ End.

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