1991-2020 Degrees Fahrenheit 1 48.7 49.9 -1.2 21 51 1952,1987 1963 1959 1963 bottom-third 2 55.0 56.1 -1.1 20 52 2006 1963 1959 1963 bottom-third 1975,1999,2002 3 59.3 60.7 -1.4 16 55 1992 2021 1957 1963 bottom-third 1957,1989 4 63.0 63.5 -0.5 21 50 1992 1955 1962 1963 bottom-third 1965,1977,2020 5 64.1 64.5 -0.4 26 45 1992 2021 1962 1963 normal 1968,1979 6 63.9 63.6 0.3 43 28 1992 2021 1962 1963 normal 7 61.6 61.3 0.3 45 26 1992 1955 1962 1963 normal 1959,2018 8 57.7 58.0 -0.3 31 40 1951,1996 2012 1962 1963 normal 9 54.2 54.1 0.1 47 24 2014 2012 1962 1963 normal 1952,1970,1976,2004 10 51.3 50.6 0.7 50 20 1979 2012 1963 1955 top-third 11 47.7 48.2 -0.5 34 36 2014 2012 1963 1963 normal 1963 12 47.1 47.2 -0.1 42 28 2014 2012 1963 1955 normal 18 53.3 52.7 0.6 54 15 2014 2012 1963 1955 top-third 1987 24 47.0 47.2 -0.2 40 28 1979 2017 1963 1956 normal 1995 36 46.4 47.2 -0.8 22 44 1979 2000 1963 1958 bottom-third 1966,1995 48 46.5 47.2 -0.7 22 42 1980 2007,2018 1963 1958 normal 1966,1973,1974,1987,1994 60 46.3 47.2 -0.9 13 49 1979 2002 1963 1959 bottom-third 1965,1966,1970