1991-2020 Degrees Fahrenheit 1 34.8 38.2 -3.4 28 56 1989 2015 1950 1953 bottom-third 2 39.4 42.6 -3.2 20 63 1989 2015 1951 1953 bottom-third 1951,1981 3 46.3 47.6 -1.3 39 44 1976 2015 1952 1953 normal 4 51.8 53.1 -1.3 38 45 1976 2015 1952 1953 normal 1948,1974,1991 5 56.0 57.8 -1.8 31 52 1976 2015 1952 1953 normal 1947,1951 6 59.6 61.2 -1.6 35 48 1976 2015 1952 1953 normal 1946,1952 7 61.4 62.9 -1.5 39 43 1976 2015 1951 1953 normal 8 61.3 63.0 -1.7 30 52 1976 2015 1951 1953 normal 1974,1995 9 60.7 62.0 -1.3 42 40 1967 2015 1951 1953 normal 1980,1985 10 58.8 60.1 -1.3 36 45 1967 2015 1952 1953 normal 1941,1952,1983,1986,1993 11 57.1 57.9 -0.8 52 29 1967 2012 1952 1953 normal 1955,1957,1994 12 54.8 55.9 -1.1 50 31 1958 2012 1951 1953 normal 1957 18 56.7 57.6 -0.9 55 25 1963 2016 1952 1953 top-third 1971,1974,1975 24 55.4 55.8 -0.4 56 22 1963 2021 1952 1953 top-third 2005 36 55.3 55.8 -0.5 52 23 1963 2021 1953 1954 top-third 1955,1991 48 55.1 55.7 -0.6 47 25 1963,1969 2022 1953 1954 normal 2003 60 54.8 55.7 -0.9 39 30 1967,1969,1970 2020,2021 1952 1953 normal 1991