1991-2020 Degrees Fahrenheit 1 69.1 72.3 -3.2 10 66 1972 1952,2010 1955 1957 bottom-third 2 66.5 68.5 -2.0 14 62 1961 2018 1955 1957 bottom-third 1980,1990 3 62.4 64.7 -2.3 9 67 1961 1991 1958 1957 bottom-third 1979,1982,1990 4 56.5 60.0 -3.5 3 73 1960 1991,2012 1958 1957 bottom-tenth 5 50.7 55.6 -4.9 1 75 1958 2012 1958 1957 lowest 6 47.3 52.2 -4.9 2 74 1978 2012 1958 1957 bottom-tenth 7 46.3 50.3 -4.0 4 72 1978 2012 1958 1957 bottom-tenth 8 46.3 49.8 -3.5 5 70 1977 2012 1958 1957 bottom-tenth 9 47.0 50.6 -3.6 4 71 1977 2012 1958 1957 bottom-tenth 10 49.3 52.4 -3.1 4 70 1977 2017 1958 1957 bottom-tenth 1968 11 51.5 54.4 -2.9 5 69 1977 2017 1958 1957 bottom-tenth 12 53.5 56.2 -2.7 5 69 1977 2017 1958 1957 bottom-tenth 18 53.2 54.9 -1.7 16 58 1978,1979 2017 1958 1957 bottom-third 1984 24 55.1 56.1 -1.0 23 50 1978 2017 1958 1957 bottom-third 1960,1996 36 55.1 56.1 -1.0 23 49 1979 2018 1958 1957 bottom-third 1959,1972,1998 48 55.2 56.1 -0.9 25 46 1980 2019 1958 1957 normal 1996,1998 60 55.4 56.0 -0.6 27 43 1981 2020 1958 1957 normal 1986,1996