1991-2020 Degrees Fahrenheit 1 33.4 35.5 -2.1 37 47 1979 2017 1945 1946 normal 2 33.0 34.4 -1.4 47 37 1978 2023 1945 1946 normal 3 31.6 35.7 -4.1 20 64 1977 2016 1945 1944 bottom-third 4 -99 38.5 -99 -99 -99 1977 2016 normal 5 -99 42.3 -99 -99 -99 1977 2016 normal 6 -99 46.8 -99 -99 -99 1977 2016 normal 7 -99 51.1 -99 -99 -99 1977 2016 normal 8 -99 54.4 -99 -99 -99 1977 2016 normal 9 -99 56.5 -99 -99 -99 1977 2016 normal 10 -99 57.2 -99 -99 -99 1977 2016 normal 11 -99 56.9 -99 -99 -99 1977 2016 normal 12 -99 55.8 -99 -99 -99 1968 2017 normal 18 -99 52.8 -99 -99 -99 1978 2017 normal 24 -99 55.7 -99 -99 -99 1945,1964,1968,1969,1978 2017 normal 36 -99 55.7 -99 -99 -99 1963,1970 2018 normal 48 -99 55.6 -99 -99 -99 1964,1970 2023 normal 60 -99 55.6 -99 -99 -99 1970 2020 normal