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History of Ice Freezing and Thawing on Lake Mendota

View the ice-over and ice-out dates, and duration of ice cover, for Lake Mendota dating back to 1852.

Annual Duration of Ice Cover

Click and drag anywhere on the chart to zoom in on specific data points.

Longest Duration

161 days
(1880-81)

Shortest Duration

21 days
(2001-02)

Average Duration

102 days

Five-Year Running Average

83 days

Freeze and Thaw Dates

Winter Freeze-Over Date Thaw Date Days of Ice Cover
2023-24 January 15 February 28 44
2022-23 December 25 April 2 98
2021-22 January 7 April 2 85
2020-21 January 3 March 20 76
2019-20 January 12 March 22 70
2018-19 January 10 March 31 86
2018-19 December 15 December 21
2017-18 December 27 March 31 94
2016-17 January 1 March 7 65
2015-16 January 11 March 13 62
2014-15 January 2 April 3 91
2013-14 December 16 April 12 117
2012-13 January 14 April 11 87
2011-12 January 14 March 11 57
2010-11 December 15 April 3 109
2009-10 December 29 March 26 87
2008-09 December 16 March 23 97
2007-08 December 26 April 10 106
2006-07 January 20 March 27 66
2005-06 December 19 March 24 95
2004-05 December 25 April 5 101
2003-04 January 7 March 27 80
2002-03 January 4 April 3 89
2001-02 March 4 March 15 21
2001-02 January 2 January 12
2000-01 December 13 April 7 115
1999-00 January 14 March 7 53
1998-99 December 30 March 21 82
1997-98 January 11 February 27 47
1996-97 December 20 April 1 102
1995-96 December 10 April 7 119
1994-95 January 6 March 21 74
1993-94 December 27 March 31 94
1992-93 December 24 April 11 108
1991-92 December 18 March 26 99
1990-91 December 26 March 24 88
1989-90 December 12 March 15 93
1988-89 December 29 April 5 97
1987-88 January 2 March 29 87
1986-87 December 13 March 12 89
1985-86 December 14 March 31 107
1984-85 January 2 March 27 85
1984-85 December 25 December 26
1983-84 December 19 April 8 111
1982-83 January 13 March 8 54
1981-82 December 28 April 3 96
1980-81 December 20 March 23 93
1979-80 December 29 April 6 99
1978-79 December 25 April 19 118
1978-79 December 10 December 13
1977-78 December 10 April 11 123
1977-78 December 7 December 8
1976-77 December 3 March 28 115
1975-76 December 27 March 24 88
1974-75 January 2 April 19 107
1973-74 December 21 April 5 105
1972-73 December 7 March 14 97
1971-72 January 5 April 19 105
1970-71 December 24 April 13 110
1969-70 December 16 April 8 113
1968-69 December 25 April 10 108
1968-69 December 17 December 19
1967-68 December 27 March 27 91
1966-67 December 26 April 3 98
1965-66 January 11 March 17 65
1964-65 December 15 April 14 120
1963-64 December 20 April 11 113
1962-63 December 12 April 3 112
1961-62 December 16 April 12 117
1960-61 December 19 April 6 108
1959-60 December 29 April 12 105
1958-59 December 9 April 14 126
1957-58 December 30 April 4 95
1956-57 December 14 April 4 111
1955-56 December 12 April 4 114
1954-55 January 2 April 4 92
1953-54 December 30 March 25 85
1952-53 December 30 March 21 81
1951-52 December 16 April 8 114
1950-51 December 11 April 12 122
1949-50 December 23 April 11 109
1948-49 December 24 March 30 96
1947-48 December 21 April 3 104
1946-47 December 30 April 10 101
1945-46 December 13 March 21 98
1944-45 December 18 March 20 92
1943-44 December 16 April 8 114
1942-43 December 7 April 2 116
1941-42 January 3 March 26 82
1940-41 January 5 April 11 96
1939-40 January 2 April 16 105
1938-39 December 28 April 4 97
1937-38 December 7 March 22 105
1936-37 January 5 April 13 121
1936-37 December 7 December 30
1935-36 December 20 March 30 101
1934-35 December 24 March 28 94
1933-34 December 25 March 26 91
1932-33 December 10 April 4 115
1931-32 January 30 April 4 65
1930-31 December 16 March 24 98
1929-30 December 3 March 20 107
1928-29 December 21 March 27 96
1927-28 December 17 April 1 106
1926-27 December 6 March 19 103
1925-26 December 16 April 19 124
1924-25 December 19 April 3 105
1923-24 January 1 April 14 104
1922-23 December 16 April 20 125
1921-22 December 25 March 31 96
1920-21 December 25 March 16 81
1919-20 December 9 March 28 110
1918-19 January 3 March 26 82
1917-18 December 11 April 5 115
1916-17 December 16 April 11 116
1915-16 December 28 April 8 102
1914-15 December 16 April 10 115
1913-14 January 12 April 10 88
1912-13 December 24 April 2 99
1911-12 December 28 April 14 108
1910-11 December 9 March 20 101
1909-10 December 18 March 26 98
1908-09 December 22 April 7 106
1907-08 January 1 March 24 83
1906-07 December 20 March 24 94
1905-06 January 1 April 8 97
1904-05 December 14 April 1 108
1903-04 December 13 April 17 126
1902-03 December 25 March 24 89
1901-02 December 15 March 30 105
1900-01 December 25 April 11 107
1899-00 December 27 April 17 111
1898-99 December 9 April 18 130
1897-98 December 17 March 27 100
1896-97 December 21 April 10 110
1895-96 January 5 April 5 91
1894-95 December 28 April 8 101
1893-94 December 4 March 15 101
1892-93 December 16 April 7 112
1891-92 December 27 April 2 97
1890-91 December 26 April 16 111
1889-90 January 14 March 30 75
1888-89 January 2 March 31 88
1887-88 December 24 April 15 113
1886-87 December 5 April 15 131
1885-86 December 12 April 19 128
1884-85 December 17 April 20 124
1883-84 December 18 April 15 119
1882-83 December 10 April 13 124
1881-82 January 2 March 21 78
1880-81 November 23 May 3 161
1879-80 December 17 March 25 99
1878-79 December 21 April 12 112
1877-78 January 6 March 9 62
1876-77 December 8 April 17 130
1875-76 January 10 April 10 91
1874-75 December 10 April 15 126
1873-74 November 29 April 14 136
1872-73 November 30 April 23 144
1871-72 December 19 April 23 126
1870-71 December 24 April 2 99
1869-70 December 2 April 12 131
1868-69 December 10 April 16 127
1867-68 December 12 March 31 110
1866-67 December 18 April 20 123
1865-66 December 14 April 18 125
1864-65 December 8 April 5 118
1863-64 December 18 April 21 125
1862-63 December 26 April 9 104
1861-62 December 2 April 13 132
1860-61 December 14 April 10 117
1859-60 December 7 March 26 110
1858-59 December 8 March 14 96
1857-58 November 25 March 26 121
1856-57 December 6 May 6 151
1855-56 December 18 April 14 118
1854-55
1853-54 December 27
1852-53 April 5