1991-2020 Degrees Fahrenheit 1 67.5 69.9 -2.4 20 55 1972 2005 1955 1954 bottom-third 2 62.0 65.7 -3.7 11 64 1961 1991 1956 1955 bottom-third 3 56.3 60.7 -4.4 4 71 1961 1991 1950 1955 bottom-tenth 1966 4 50.6 55.3 -4.7 5 70 1950,1972 1991 1950 1955 bottom-tenth 5 46.5 50.3 -3.8 9 66 1978 1991 1950 1955 bottom-third 6 42.9 46.6 -3.7 8 67 1978 2012 1956 1955 bottom-third 1960 7 40.5 44.6 -4.1 5 70 1978 2012 1956 1955 bottom-tenth 1958 8 40.0 44.4 -4.4 4 70 1978 2012 1956 1955 bottom-tenth 9 41.4 45.5 -4.1 5 69 1978 2012 1956 1955 bottom-tenth 1977 10 43.8 47.5 -3.7 5 69 1978 2012 1951 1955 bottom-tenth 1951,1961 11 46.5 49.7 -3.2 9 65 1963,1977,1978 2017 1951 1955 bottom-third 12 49.0 51.7 -2.7 13 61 1977 2012,2017 1951 1955 bottom-third 1972 18 47.7 50.0 -2.3 21 52 1979 2017 1952 1955 bottom-third 1960,1973 24 49.5 51.6 -2.1 20 52 1978 2017 1952 1955 bottom-third 1965,1966,1967,1971,1994 36 49.9 51.6 -1.7 26 44 1979 2018 1953 1955 normal 48 50.0 51.5 -1.5 29 39 1980 2019,2022 1954 1955 normal 1996 60 49.9 51.5 -1.6 27 39 1981 2020 1955 1956 normal