1991-2020 Degrees Fahrenheit 1 12.8 17.3 -4.5 21 55 1992 2003 1975 1976 bottom-third 2 12.8 17.8 -5.0 14 60 1992 1981 1975 1976 bottom-third 1962 3 17.8 22.0 -4.2 13 61 1992 2018 1975 1976 bottom-third 1962 4 23.1 27.5 -4.4 8 66 1992 2018 1973 1976 bottom-third 1965 5 29.3 33.2 -3.9 8 66 1992 2018 1975 1976 bottom-third 6 34.4 38.2 -3.8 8 66 1992 2018 1975 1976 bottom-third 7 38.7 42.1 -3.4 8 66 1992 2018 1975 1976 bottom-third 8 41.0 44.5 -3.5 5 69 1992 2018 1975 1976 bottom-tenth 1975,1988 9 42.1 45.3 -3.2 8 66 1992 2018 1973 1976 bottom-third 10 42.1 45.0 -2.9 9 65 1992 2018 1976 1974 bottom-third 11 41.1 44.1 -3.0 8 66 1992 2018 1976 1975 bottom-third 12 40.1 42.5 -2.4 19 55 1965 2018 1976 1971 bottom-third 1962 18 38.6 41.1 -2.5 15 57 1993 2018 1976 1972 bottom-third 1969 24 39.7 42.5 -2.8 6 66 1993 2018 1976 1974 bottom-tenth 1974,1980,1994 36 39.5 42.4 -2.9 3 67 1976,1994 2018 1976 1975 bottom-tenth 1993 48 39.6 42.2 -2.6 2 66 1976 2019 1976 1975 bottom-tenth 1975 60 39.6 42.1 -2.5 2 64 1976 2020,2021,2022 1976 1975 bottom-tenth