1991-2020 Degrees Fahrenheit 1 31.7 34.0 -2.3 28 35 1977 2023 1962 1962 normal 2 32.4 36.0 -3.6 17 46 1977 2002 1962 1962 bottom-third 1971 3 -99 39.3 -99 -99 -99 1977 2002 normal 4 -99 43.6 -99 -99 -99 1977 2002 normal 5 -99 48.6 -99 -99 -99 1977 2017 normal 6 -99 53.2 -99 -99 -99 1977 2017 normal 7 -99 56.6 -99 -99 -99 1977 2017 normal 8 -99 58.6 -99 -99 -99 1977 2017 normal 9 -99 59.2 -99 -99 -99 1977 2017 normal 10 -99 58.8 -99 -99 -99 1977 2020 normal 11 -99 57.5 -99 -99 -99 1977 2017 normal 12 -99 55.7 -99 -99 -99 1968,1977 2017 normal 18 -99 54.8 -99 -99 -99 1978 2017 normal 24 -99 55.7 -99 -99 -99 1968,1982 2013,2021 normal 36 -99 55.7 -99 -99 -99 1982 2022,2023 normal 48 -99 55.7 -99 -99 -99 1982 2023 normal 60 -99 55.6 -99 -99 -99 1971,1981,1982,1983,1984 2023 normal