1991-2020 Degrees Fahrenheit 1 10.1 20.5 -10.4 3 80 2014 1998 1967 1966 bottom-tenth 2 13.7 18.6 -4.9 23 59 1963 2002 1966 1964 bottom-third 3 15.9 19.9 -4.0 23 59 2014 2002 1965 1966 bottom-third 1957 4 20.1 23.6 -3.5 23 57 1977 2002 1965 1966 bottom-third 1945,1982 5 25.6 28.6 -3.0 22 58 1977 2002 1965 1966 bottom-third 1945,1968 6 31.1 34.0 -2.9 20 60 1977 2002 1965 1966 bottom-third 7 36.2 39.1 -2.9 19 61 1977 2002 1965 1966 bottom-third 8 40.9 43.1 -2.2 24 56 1977 2002 1966 1966 bottom-third 1955,1966 9 43.9 45.8 -1.9 22 58 1977 2002 1966 1964 bottom-third 1957,1972,1996,2009 10 44.7 47.0 -2.3 18 62 1977 2002 1965 1966 bottom-third 1955 11 44.5 46.8 -2.3 18 62 1951 2002 1965 1966 bottom-third 1957 12 43.5 45.6 -2.1 25 55 1951 2002 1966 1964 bottom-third 1945 18 39.7 41.7 -2.0 22 55 1952 2017 1966 1965 bottom-third 1953,1990 24 43.2 45.6 -2.4 10 67 1952 2017 1966 1965 bottom-third 1946,1971 36 43.1 45.6 -2.5 5 70 1953 2013,2018 1963 1966 bottom-tenth 48 43.8 45.6 -1.8 24 49 1968 2002 1966 1961 bottom-third 1947,1974,1975,1997 60 43.5 45.6 -2.1 13 58 1970 2002 1966 1965 bottom-third 1965,1968,1974,1997