1991-2020 Degrees Fahrenheit 1 34.4 36.5 -2.1 23 49 1959 2001 2000 2001 bottom-third 2 40.1 43.2 -3.1 12 60 1959 1963 1996 2001 bottom-third 1952 3 48.1 49.6 -1.5 20 52 1976 2016 1996 2001 bottom-third 1974,1986,1989 4 53.6 54.7 -1.1 23 48 1976 2016 1997 2001 bottom-third 1965,1995 5 57.7 58.1 -0.4 31 40 1992 2016 1997 2001 normal 6 59.7 59.8 -0.1 39 32 1951 2016 2000 2001 normal 1978 7 59.0 59.7 -0.7 27 44 1951 2016 1997 2001 normal 8 57.6 58.2 -0.6 29 42 1951 2016 1997 2001 normal 1952,1960 9 54.7 55.6 -0.9 28 43 1951 2012,2016 1997 2001 normal 1984,2008 10 52.1 52.4 -0.3 41 30 1951 2012,2016 1997 2001 normal 1980,1994 11 50.0 49.3 0.7 53 17 2014 2012 2001 2000 top-third 12 48.3 47.2 1.1 57 13 2014 2012 2001 2000 top-third 18 52.5 51.4 1.1 60 9 2014 2016 2001 2000 top-third 2000,2005 24 47.4 47.2 0.2 50 18 1979 2017 1997 2001 top-third 1955,2003 36 47.8 47.2 0.6 56 10 1979 2000 1998 2001 top-third 2013,2021 48 48.0 47.2 0.8 59 5 1979 2001 1999 2001 top-tenth 2019 60 48.4 47.2 1.2 61 1 1979 2002 2001 2002 highest