A Christmas cold snap and low wind helped Lake Mendota officially freeze on Wednesday, December 27. Lake Mendota is the largest lake in the Yahara Watershed. The lake froze 17 days after the smallest lake in the watershed, Lake Wingra, which officially froze on December 10.
The Wisconsin State Climatology Office requires ice to hold for a period of 24 hours before a lake can officially be declared frozen over. After ice took shape on December 26, staff waited to see whether it would hold out through the night. The December 27 freeze date is five days ahead of last winter’s January 1 freeze date, and only seven days later than the December 20 median freeze date. The latest freeze date for Lake Mendota was January 30 – which happened in the winter of 1932.