1991-2020 Degrees Fahrenheit 1 34.2 38.2 -4.0 17 60 1978 1976 2015 2020 bottom-third 2 34.5 36.6 -2.1 28 49 1978 2017 2015 2020 normal 3 35.5 37.4 -1.9 31 46 1977 2017 2015 2020 normal 1985,1986 4 39.2 39.6 -0.4 41 35 1977 2017 2015 2020 normal 5 43.0 43.1 -0.1 45 31 1977 2017 2015 2020 normal 6 47.1 47.3 -0.2 45 30 1977 2017 2015 2020 normal 1960,1962 7 51.2 51.2 0.0 50 25 1977 2017 2015 2020 top-third 1997,2000 8 54.8 54.3 0.5 55 20 1977 2017 2018 2020 top-third 2000 9 56.7 56.3 0.4 53 22 1977 2017 2018 2020 top-third 2005 10 57.1 57.1 0.0 46 29 1977 2017 2015 2020 normal 1988 11 56.7 57.1 -0.4 43 32 1977 2017 2015 2020 normal 1956,1957,1988 12 56.3 56.2 0.1 54 21 1977 2017 2015 2020 top-third 1953,1960,2000,2002,2006 18 54.2 53.2 1.0 68 6 1978 2017 2019 2020 top-tenth 2023 24 57.2 56.1 1.1 68 6 1978 2017 2019 2020 top-tenth 2012 36 57.1 56.1 1.0 68 5 1979 2018 2017 2020 top-tenth 2022 48 57.0 56.1 0.9 68 4 1980 2020 2018 2020 top-tenth 2022 60 57.4 56.0 1.4 69 2 1981 2020 2019 2020 top-tenth