1991-2020 Degrees Fahrenheit 1 39.1 38.2 0.9 47 30 1978 1976 1948 1948 normal 2 32.3 36.6 -4.3 15 62 1978 2017 1948 1948 bottom-third 1970 3 33.5 37.4 -3.9 13 64 1977 2017 1948 1948 bottom-third 4 -99 39.6 -99 -99 -99 1977 2017 normal 5 -99 43.1 -99 -99 -99 1977 2017 normal 6 -99 47.3 -99 -99 -99 1977 2017 normal 7 -99 51.2 -99 -99 -99 1977 2017 normal 8 -99 54.3 -99 -99 -99 1977 2017 normal 9 -99 56.3 -99 -99 -99 1977 2017 normal 10 -99 57.1 -99 -99 -99 1977 2017 normal 11 -99 57.1 -99 -99 -99 1977 2017 normal 12 -99 56.2 -99 -99 -99 1977 2017 normal 18 -99 53.2 -99 -99 -99 1978 2017 normal 24 -99 56.1 -99 -99 -99 1978 2017 normal 36 -99 56.1 -99 -99 -99 1979 2018 normal 48 -99 56.1 -99 -99 -99 1964,1980 2020 normal 60 -99 56.1 -99 -99 -99 1981 2020 normal