1991-2020 Degrees Fahrenheit 1 48.0 53.4 -5.4 2 76 1949 2015 1949 1955 bottom-tenth 2 49.1 52.3 -3.2 11 67 1949 2015 1955 1954 bottom-third 3 50.1 51.9 -1.8 25 53 1949 2015 1955 1954 bottom-third 4 51.0 53.0 -2.0 20 58 1949 2015 1955 1954 bottom-third 1965,1974,1989,2001 5 52.8 54.9 -2.1 19 59 1949 2015 1955 1954 bottom-third 1971,2001 6 54.2 56.6 -2.4 11 67 1949 2015 1955 1954 bottom-third 7 55.2 57.7 -2.5 4 74 1949 2015 1955 1954 bottom-tenth 1957 8 55.8 58.5 -2.7 4 73 1949 2015 1955 1954 bottom-tenth 9 56.2 58.9 -2.7 4 72 1949 2015 1955 1954 bottom-tenth 10 56.4 59.0 -2.6 5 71 1949 2015 1955 1954 bottom-tenth 11 56.0 58.8 -2.8 3 73 1949 2015 1950 1955 bottom-tenth 12 55.7 58.5 -2.8 4 72 1949 2015 1955 1954 bottom-tenth 18 54.8 57.8 -3.0 3 72 1949,1950 2016 1950 1955 bottom-tenth 24 55.6 58.4 -2.8 2 72 1950 2016 1950 1955 bottom-tenth 36 55.9 58.4 -2.5 4 68 1950 2017 1951 1955 bottom-tenth 48 56.0 58.4 -2.4 3 67 1952 2018 1955 1955 bottom-tenth 1955 60 56.0 58.3 -2.3 2 66 1953 2018 1953 1955 bottom-tenth 1952,1957