1991-2020 Degrees Fahrenheit 1 48.8 41.5 7.3 78 2 1977 1950 1973 1950 top-tenth 2 45.4 42.9 2.5 70 10 1977 2016 1973 1972 top-third 1949 3 48.3 45.6 2.7 75 5 1977 2016 1973 1974 top-tenth 1999 4 51.7 49.6 2.1 74 6 1977 2016 1973 1974 top-tenth 1991 5 55.9 54.1 1.8 72 8 1977 2020 1973 1974 top-tenth 6 59.3 58.1 1.2 71 9 1977 2008 1973 1974 top-third 1991,2007 7 61.6 61.3 0.3 65 15 1977 2017 1973 1974 top-third 2002 8 63.3 63.1 0.2 63 17 1977 2012,2017 1973 1974 top-third 2005 9 63.4 63.7 -0.3 59 20 1977 2020 1973 1950 top-third 2009,2018 10 62.8 63.4 -0.6 53 26 1977 2012,2020 1973 1950 top-third 1950 11 62.0 62.3 -0.3 57 22 1961,1968 2017 1973 1974 top-third 1995,2003 12 60.1 60.8 -0.7 52 27 1948 2012 1973 1950 normal 18 58.6 59.9 -1.3 46 33 1964 2017 1973 1972 normal 1972,2014 24 58.8 60.8 -2.0 28 50 1969 2013 1973 1972 normal 36 59.0 60.7 -1.7 29 48 1970 2021 1973 1958 normal 1950,1986,1990 48 59.0 60.7 -1.7 29 47 1970 2020 1973 1958 normal 1954,1986 60 58.6 60.6 -2.0 22 53 1970 2021 1973 1960 bottom-third