1991-2020 Degrees Fahrenheit 1 35.3 38.2 -2.9 20 57 1978 1976 1968 1972 bottom-third 2 34.6 36.6 -2.0 29 48 1978 2017 1971 1972 normal 1995,2009 3 37.1 37.4 -0.3 45 32 1977 2017 1971 1972 normal 4 38.7 39.6 -0.9 34 42 1977 2017 1971 1972 normal 5 41.5 43.1 -1.6 29 47 1977 2017 1971 1972 normal 6 46.2 47.3 -1.1 34 41 1977 2017 1971 1972 normal 1971,2009 7 50.1 51.2 -1.1 29 46 1977 2017 1970 1972 normal 2003 8 53.1 54.3 -1.2 25 50 1977 2017 1970 1972 bottom-third 9 54.5 56.3 -1.8 14 61 1977 2017 1970 1972 bottom-third 1975,1996,2004 10 55.6 57.1 -1.5 18 57 1977 2017 1970 1972 bottom-third 1969,1975,1981 11 55.5 57.1 -1.6 15 60 1977 2017 1970 1972 bottom-third 1951,1981,1998,2004 12 54.5 56.2 -1.7 14 61 1977 2017 1970 1972 bottom-third 1978,1979,2010 18 53.1 53.2 -0.1 49 25 1978 2017 1972 1955 normal 1955,2007,2009 24 55.4 56.1 -0.7 32 42 1978 2017 1971 1972 normal 36 55.6 56.1 -0.5 38 35 1979 2018 1972 1957 normal 1953,1957,2004 48 55.1 56.1 -1.0 21 51 1964,1980 2020 1971 1972 bottom-third 1959,1998 60 55.1 56.1 -1.0 22 49 1981 2020 1972 1960 bottom-third 1998