Søre Illåbrean is a north-facing valley glacier at the eastern side of Leirdalen in Jotunheimen.
| Year | Front variation (m) | Cumulative front variation (m) |
|---|---|---|
| 1902 | 0 | Start |
| 1904 | 2 | 2 |
| 1905 | -13 | -11 |
| 1906 | 2 | -9 |
| 1907 | -12 | -21 |
| 1908 | 0 | -21 |
| 1909 | -17 | -38 |
| 1910 | -4 | -42 |
| 1911 | -8 | -50 |
| 1912 | -12 | -62 |
| 1933 | -105 | -167 |
| 1934 | -13 | -180 |
| 1935 | -13 | -193 |
| 1936 | -5 | -198 |
| 1937 | -7 | -205 |
| 1938 | -18 | -223 |
| 1939 | -12 | -235 |
| 1940 | -35 | -270 |
| 1941 | -20 | -290 |
| 1942 | -10 | -300 |
| 1943 | 0 | -300 |
| 1944 | -10 | -310 |
| 1945 | -15 | -325 |
| 1946 | -33 | -358 |
| 1947 | -30 | -388 |
| 1948 | -16 | -404 |
| 1949 | -19 | -423 |
| 1950 | -44 | -467 |
| 1951 | -12 | -479 |
| 1952 | -14 | -493 |
| 1953 | -29 | -522 |
| 1954 | -12 | -534 |
| 1955 | -5 | -539 |
| 1956 | -17 | -556 |
| 1957 | -18 | -574 |
| 1958 | -22 | -596 |
| 1959 | -25 | -621 |
| 1960 | -18 | -639 |
| 1961 | -16 | -655 |
| 1971 | -107 | -762 |
| 1975 | -42 | -804 |
| 1976 | -42 | -846 |
| 1979 | -31 | -877 |