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
75 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 |