Historical Monthly Mean Water Levels from the Coordinated network for Lake Ontario

Monthly mean water levels in metres referred to IGLD 1985

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average Min Max Range
1918 74.74 74.72 74.92 75.10 75.09 75.06 74.99 74.87 74.78 74.74 74.74 74.72 74.87 74.72 75.10 0.38
1919 74.76 74.72 74.76 74.92 75.18 75.36 75.28 75.16 75.01 74.87 74.78 74.67 74.96 74.67 75.36 0.69
1920 74.54 74.44 74.46 74.60 74.64 74.62 74.66 74.64 74.59 74.53 74.51 74.58 74.57 74.44 74.66 0.22
1921 74.61 74.58 74.70 74.88 74.96 74.92 74.84 74.71 74.56 74.46 74.39 74.38 74.67 74.38 74.96 0.58
1922 74.36 74.34 74.47 74.76 74.92 74.96 75.02 74.90 74.75 74.61 74.47 74.32 74.66 74.32 75.02 0.70
1923 74.30 74.27 74.36 74.54 74.62 74.72 74.68 74.55 74.44 74.32 74.24 74.28 74.44 74.24 74.72 0.48
1924 74.34 74.40 74.39 74.55 74.76 74.82 74.79 74.75 74.62 74.56 74.41 74.30 74.56 74.30 74.82 0.52
1925 74.20 74.26 74.50 74.62 74.62 74.56 74.49 74.40 74.30 74.22 74.23 74.28 74.39 74.20 74.62 0.42
1926 74.20 74.15 74.16 74.41 74.55 74.55 74.49 74.44 74.41 74.41 74.50 74.56 74.40 74.15 74.56 0.41
1927 74.50 74.52 74.65 74.73 74.73 74.77 74.74 74.66 74.52 74.44 74.40 74.62 74.61 74.40 74.77 0.37
1928 74.74 74.73 74.72 74.87 74.93 74.93 74.97 74.94 74.79 74.67 74.64 74.68 74.80 74.64 74.97 0.33
1929 74.68 74.67 74.79 75.14 75.45 75.49 75.46 75.34 75.18 75.03 74.92 74.87 75.08 74.67 75.49 0.82
1930 74.98 75.08 75.24 75.36 75.38 75.39 75.37 75.19 75.00 74.82 74.64 74.52 75.08 74.52 75.39 0.87
1931 74.42 74.36 74.34 74.43 74.48 74.57 74.51 74.42 74.30 74.20 74.14 74.12 74.36 74.12 74.57 0.45
1932 74.26 74.46 74.51 74.69 74.79 74.76 74.70 74.61 74.44 74.32 74.26 74.23 74.50 74.23 74.79 0.56
1933 74.24 74.21 74.20 74.39 74.54 74.57 74.48 74.38 74.26 74.10 73.98 73.96 74.28 73.96 74.57 0.61
1934 74.04 74.05 74.06 74.24 74.29 74.22 74.14 74.00 73.91 73.82 73.75 73.74 74.02 73.74 74.29 0.55
1935 73.81 73.86 73.94 74.03 74.11 74.19 74.24 74.16 74.04 73.92 73.88 73.87 74.00 73.81 74.24 0.43
1936 73.84 73.78 73.98 74.45 74.53 74.48 74.38 74.23 74.16 74.08 74.06 74.00 74.16 73.78 74.53 0.75
1937 74.14 74.34 74.39 74.47 74.70 74.77 74.76 74.69 74.55 74.40 74.40 74.34 74.50 74.14 74.77 0.63
1938 74.28 74.38 74.54 74.70 74.74 74.72 74.66 74.64 74.52 74.46 74.36 74.27 74.52 74.27 74.74 0.47
1939 74.24 74.26 74.42 74.68 74.80 74.78 74.74 74.66 74.51 74.38 74.26 74.18 74.49 74.18 74.80 0.62
1940 74.12 74.08 74.08 74.37 74.62 74.73 74.75 74.66 74.54 74.42 74.36 74.38 74.43 74.08 74.75 0.67
1941 74.50 74.52 74.53 74.62 74.60 74.53 74.46 74.37 74.28 74.18 74.16 74.14 74.41 74.14 74.62 0.48
1942 74.14 74.14 74.30 74.58 74.70 74.79 74.74 74.69 74.60 74.52 74.50 74.50 74.52 74.14 74.79 0.65
1943 74.64 74.72 74.89 75.06 75.33 75.60 75.54 75.44 75.29 75.10 75.06 74.94 75.13 74.64 75.60 0.96
1944 74.80 74.72 74.72 74.88 75.06 75.12 75.11 75.00 74.88 74.73 74.59 74.54 74.85 74.54 75.12 0.58
1945 74.53 74.54 74.76 75.04 75.22 75.34 75.33 75.24 75.12 75.22 75.18 75.20 75.06 74.53 75.34 0.81
1946 75.16 75.10 75.20 75.16 75.11 75.13 75.10 74.98 74.84 74.76 74.72 74.66 74.99 74.66 75.20 0.54
1947 74.68 74.78 74.80 75.07 75.28 75.63 75.66 75.58 75.41 75.18 75.02 74.94 75.17 74.68 75.66 0.98
1948 74.86 74.84 75.02 75.32 75.42 75.46 75.38 75.24 75.05 74.88 74.78 74.72 75.08 74.72 75.46 0.74
1949 74.74 74.84 74.94 75.03 75.06 74.98 74.85 74.70 74.57 74.48 74.36 74.34 74.74 74.34 75.06 0.72
1950 74.52 74.68 74.78 75.10 75.17 75.15 75.09 74.99 74.88 74.78 74.74 74.82 74.89 74.52 75.17 0.65
1951 74.89 74.98 75.18 75.47 75.62 75.59 75.56 75.39 75.24 75.06 74.98 75.00 75.25 74.89 75.62 0.73
1952 75.10 75.27 75.37 75.62 75.72 75.76 75.64 75.48 75.32 75.15 74.98 74.98 75.37 74.98 75.76 0.78
1953 74.94 74.94 75.00 75.17 75.30 75.34 75.23 75.12 74.98 74.82 74.69 74.65 75.02 74.65 75.34 0.69
1954 74.62 74.68 74.89 75.09 75.32 75.30 75.18 75.02 74.92 74.90 74.92 74.94 74.98 74.62 75.32 0.70
1955 75.02 74.98 75.18 75.44 75.49 75.42 75.27 75.14 74.98 74.94 74.98 74.91 75.15 74.91 75.49 0.58
1956 74.78 74.69 74.76 74.95 75.23 75.30 75.20 75.06 74.99 74.82 74.68 74.60 74.92 74.60 75.30 0.70
1957 74.55 74.56 74.61 74.70 74.78 74.84 74.88 74.78 74.65 74.50 74.38 74.37 74.63 74.37 74.88 0.51
1958 74.42 74.38 74.45 74.55 74.60 74.59 74.54 74.46 74.39 74.32 74.25 74.19 74.43 74.19 74.60 0.41
1959 74.16 74.30 74.46 74.79 74.86 74.80 74.69 74.51 74.34 74.25 74.22 74.32 74.48 74.16 74.86 0.70
1960 74.45 74.56 74.59 74.87 75.11 75.14 75.00 74.80 74.61 74.50 74.49 74.43 74.71 74.43 75.14 0.71
1961 74.33 74.23 74.43 74.66 74.94 75.00 74.96 74.82 74.69 74.52 74.40 74.38 74.61 74.23 75.00 0.77
1962 74.33 74.27 74.32 74.62 74.85 74.93 74.88 74.85 74.74 74.69 74.62 74.60 74.64 74.27 74.93 0.66
1963 74.49 74.33 74.31 74.65 74.92 75.06 75.02 74.96 74.80 74.58 74.41 74.33 74.66 74.31 75.06 0.75
1964 74.18 74.02 74.02 74.27 74.54 74.67 74.68 74.57 74.43 74.20 74.00 73.86 74.29 73.86 74.68 0.82
1965 73.83 73.88 74.04 74.25 74.51 74.63 74.71 74.66 74.60 74.54 74.52 74.58 74.40 73.83 74.71 0.88
1966 74.56 74.53 74.66 74.74 74.79 74.91 74.90 74.82 74.72 74.58 74.50 74.57 74.69 74.50 74.91 0.41
1967 74.59 74.60 74.53 74.77 74.97 75.09 75.15 75.10 74.96 74.90 74.87 74.77 74.86 74.53 75.15 0.62
1968 74.67 74.69 74.70 74.90 74.90 75.02 75.08 74.98 74.86 74.66 74.53 74.60 74.80 74.53 75.08 0.55
1969 74.62 74.69 74.62 74.81 75.02 75.15 75.08 74.93 74.68 74.50 74.45 74.44 74.75 74.44 75.15 0.71
1970 74.42 74.44 74.46 74.69 74.89 74.94 74.99 74.90 74.74 74.64 74.56 74.56 74.69 74.42 74.99 0.57
1971 74.58 74.57 74.71 74.87 75.02 74.98 74.93 74.82 74.74 74.59 74.44 74.43 74.72 74.43 75.02 0.59
1972 74.54 74.63 74.73 74.95 75.21 75.26 75.34 75.25 75.02 74.78 74.71 74.80 74.94 74.54 75.34 0.80
1973 75.05 75.21 75.33 75.65 75.73 75.70 75.52 75.27 75.01 74.78 74.64 74.63 75.21 74.63 75.73 1.10
1974 74.83 75.02 75.10 75.29 75.50 75.59 75.50 75.25 74.96 74.68 74.53 74.54 75.07 74.53 75.59 1.06
1975 74.56 74.71 74.84 75.01 75.10 75.10 74.98 74.83 74.73 74.70 74.60 74.56 74.81 74.56 75.10 0.54
1976 74.62 74.71 75.07 75.37 75.54 75.54 75.42 75.22 75.00 74.83 74.67 74.54 75.04 74.54 75.54 1.00
1977 74.50 74.44 74.62 74.86 74.90 74.82 74.85 74.86 74.82 74.83 74.75 74.85 74.76 74.44 74.90 0.46
1978 75.08 75.12 74.98 75.22 75.32 75.23 75.04 74.89 74.73 74.58 74.44 74.42 74.92 74.42 75.32 0.90
1979 74.59 74.64 74.77 75.05 75.16 75.13 75.02 74.92 74.86 74.75 74.61 74.58 74.84 74.58 75.16 0.58
1980 74.60 74.61 74.60 74.99 75.14 75.13 75.12 75.06 74.88 74.66 74.55 74.54 74.82 74.54 75.14 0.60
1981 74.51 74.51 74.75 74.74 74.84 74.95 75.01 74.98 74.93 74.80 74.76 74.65 74.79 74.51 75.01 0.50
1982 74.59 74.60 74.62 74.91 75.00 75.07 75.03 74.85 74.71 74.58 74.53 74.54 74.75 74.53 75.07 0.54
1983 74.64 74.76 74.77 74.87 75.15 75.17 75.00 74.92 74.79 74.64 74.53 74.62 74.82 74.53 75.17 0.64
1984 74.73 74.76 74.90 75.12 75.30 75.32 75.21 75.02 74.82 74.63 74.52 74.49 74.90 74.49 75.32 0.83
1985 74.66 74.63 74.86 75.09 75.18 75.17 75.11 74.93 74.80 74.64 74.67 74.79 74.88 74.63 75.18 0.55
1986 74.90 74.98 75.06 75.29 75.29 75.34 75.33 75.25 75.11 75.16 75.04 75.02 75.15 74.90 75.34 0.44
1987 75.00 75.04 75.00 75.21 75.13 75.02 74.93 74.75 74.62 74.51 74.44 74.54 74.85 74.44 75.21 0.77
1988 74.53 74.59 74.59 74.75 74.88 74.92 74.86 74.80 74.68 74.56 74.54 74.46 74.68 74.46 74.92 0.46
1989 74.42 74.43 74.39 74.70 74.99 75.22 75.19 75.02 74.84 74.70 74.65 74.58 74.76 74.39 75.22 0.83
1990 74.54 74.62 74.77 74.98 75.11 75.14 75.01 74.87 74.70 74.64 74.62 74.65 74.80 74.54 75.14 0.60
1991 74.93 75.00 75.06 75.20 75.29 75.18 75.04 74.86 74.64 74.49 74.36 74.39 74.87 74.36 75.29 0.93
1992 74.44 74.45 74.56 74.84 75.11 75.05 75.00 75.03 74.98 74.85 74.82 74.86 74.83 74.44 75.11 0.67
1993 75.04 75.16 75.14 75.42 75.61 75.46 75.24 75.01 74.75 74.60 74.52 74.56 75.04 74.52 75.61 1.09
1994 74.55 74.52 74.55 74.87 75.10 75.08 75.02 74.93 74.78 74.62 74.54 74.50 74.76 74.50 75.10 0.60
1995 74.54 74.72 74.72 74.70 74.80 74.90 74.91 74.88 74.70 74.65 74.70 74.65 74.74 74.54 74.91 0.37
1996 74.62 74.75 74.77 74.82 75.13 75.23 75.15 74.99 74.83 74.74 74.72 74.73 74.87 74.62 75.23 0.61
1997 74.81 74.90 75.01 75.17 75.33 75.30 75.19 75.01 74.87 74.74 74.63 74.59 74.96 74.59 75.33 0.74
1998 74.82 75.06 75.15 75.42 75.35 75.18 75.14 74.93 74.73 74.51 74.34 74.29 74.91 74.29 75.42 1.13
1999 74.32 74.43 74.50 74.63 74.71 74.78 74.81 74.73 74.58 74.47 74.43 74.47 74.57 74.32 74.81 0.49
2000 74.50 74.45 74.58 74.82 75.10 75.26 75.24 75.06 74.81 74.61 74.46 74.47 74.78 74.45 75.26 0.81
2001 74.49 74.55 74.65 74.84 74.93 74.99 74.97 74.82 74.63 74.53 74.47 74.52 74.70 74.47 74.99 0.52
2002 74.56 74.68 74.79 74.98 75.22 75.33 75.19 74.91 74.65 74.49 74.36 74.32 74.79 74.32 75.33 1.01
2003 74.33 74.29 74.35 74.73 74.95 75.12 75.05 74.99 74.75 74.63 74.64 74.73 74.71 74.29 75.12 0.83
2004 74.83 74.75 74.72 74.89 75.04 75.14 75.09 75.02 74.95 74.70 74.50 74.55 74.85 74.50 75.14 0.64
2005 74.74 74.85 74.84 75.03 75.11 75.02 74.94 74.79 74.69 74.60 74.58 74.55 74.81 74.55 75.11 0.56
2006 74.63 74.86 74.82 74.83 74.84 74.89 74.98 74.95 74.81 74.74 74.79 74.83 74.83 74.63 74.98 0.35
2007 74.98 74.97 74.85 75.01 75.05 74.98 74.86 74.71 74.56 74.42 74.31 74.32 74.75 74.31 75.05 0.74
2008 74.56 74.75 74.87 75.18 75.30 75.19 75.12 75.06 74.81 74.60 74.51 74.55 74.88 74.51 75.30 0.79
2009 74.76 74.82 74.92 75.12 75.19 75.16 75.12 75.03 74.78 74.60 74.50 74.48 74.87 74.48 75.19 0.71
2010 74.51 74.54 74.55 74.66 74.71 74.85 74.97 74.90 74.72 74.61 74.50 74.52 74.67 74.50 74.97 0.47
2011 74.49 74.41 74.61 74.85 75.23 75.33 75.14 74.94 74.76 74.66 74.58 74.62 74.80 74.41 75.33 0.92
2012 74.80 74.99 74.97 74.92 74.91 74.90 74.79 74.65 74.50 74.34 74.29 74.28 74.70 74.28 74.99 0.71
2013 74.38 74.52 74.57 74.72 74.88 75.10 75.14 74.99 74.79 74.64 74.60 74.53 74.74 74.38 75.14 0.76
2014 74.64 74.61 74.61 74.83 75.14 75.17 75.09 74.96 74.78 74.59 74.46 74.46 74.78 74.46 75.17 0.71
2015 74.56 74.50 74.41 74.62 74.81 75.02 75.21 75.11 74.91 74.67 74.56 74.47 74.74 74.41 75.21 0.80
2016 74.63 74.82 74.97 75.11 75.09 75.02 74.95 74.84 74.70 74.54 74.48 74.46 74.80 74.46 75.11 0.65
2017 74.62 74.82 75.00 75.35 75.80 75.81 75.69 75.43 75.08 74.86 74.87 74.77 75.18 74.62 75.81 1.19
2018 74.83 74.90 74.93 75.01 75.26 75.22 75.06 74.91 74.74 74.62 74.62 74.71 74.90 74.62 75.26 0.64
2019 74.83 74.97 74.97 75.15 75.70 75.91 75.80 75.53 75.24 75.04 75.04 75.00 75.27 74.83 75.91 1.08
2020 75.05 75.12 75.18 75.32 75.36 75.29 75.18 75.05 74.85 74.70 74.60 74.62 75.03 74.60 75.36 0.76
2021 74.62 74.53 74.49 74.62 74.72 74.71 74.81 74.85 74.79 74.78 74.86 74.87 74.72 74.49 74.87 0.38
2022 74.86 74.88 74.99 75.13 75.17 75.13 74.95 74.74 74.55 74.41 74.4 74.47 74.81 74.4 75.17 0.77
2023 74.65 74.76 74.88 75.13 75.36 75.24 75.14 75.06 74.88 74.66 74.49 74.49 74.93 74.49 75.36 0.87

All-time

Average 74.58 74.62 74.69 74.89 75.03 75.07 75.01 74.90 74.75 74.62 74.54 74.53 74.77 74.43 75.10 0.67
Minimum 73.81 73.78 73.94 74.03 74.11 74.19 74.14 74.00 73.91 73.82 73.75 73.74 74.00 73.74 74.24 0.22
Maximum 75.16 75.27 75.37 75.65 75.80 75.91 75.80 75.58 75.41 75.22 75.18 75.20 75.37 74.98 75.91 1.19

2014-2023

Average 74.73 74.79 74.84 75.03 75.24 75.25 75.19 75.05 74.85 74.69 74.64 74.63

Water levels in metres referred to Chart Datum

2023 0.45 0.56 0.68 0.93 1.16 1.04 0.94 0.86 0.68 0.46 0.29 0.29
All-Time
Average 0.38 0.42 0.49 0.69 0.83 0.87 0.81 0.70 0.55 0.42 0.34 0.33
Min -0.39 -0.42 -0.26 -0.17 -0.09 -0.01 -0.06 -0.20 -0.29 -0.38 -0.45 -0.46
Max 0.96 1.07 1.17 1.45 1.60 1.71 1.60 1.38 1.21 1.02 0.98 1.00
Date modified: