1991-2020 Degrees Fahrenheit 1 18.6 19.8 -1.2 37 38 1983 2020 2017 2020 normal 2 27.3 24.8 2.5 61 14 1955 1999 2019 2020 top-third 1980 3 34.6 31.1 3.5 69 6 1951 1999 2020 2015 top-tenth 1954 4 41.9 37.8 4.1 74 1 1951 2021 2020 2021 highest 5 47.4 43.8 3.6 74 1 1951 2021 2020 2021 highest 6 51.9 48.0 3.9 74 1 1951 2021 2020 2021 highest 7 54.2 50.0 4.2 73 1 1951 2021 2020 2021 highest 8 54.0 50.3 3.7 73 1 1951 2021 2020 2021 highest 9 52.7 49.3 3.4 72 2 1951 1988 2020 1988 top-tenth 10 51.1 47.4 3.7 73 1 1951 2021 2020 2021 highest 11 47.4 44.8 2.6 70 4 1951 1987 2020 2012 top-tenth 12 45.7 42.4 3.3 72 2 1950 1987 2020 2012 top-tenth 2012 18 47.2 44.3 2.9 72 1 1951 2012,2021 2020 2012 highest 2012 24 45.1 42.4 2.7 70 2 1951 1988 2020 1988 top-tenth 36 43.3 42.3 1.0 58 12 1951 1988 2020 2017 top-third 2001 48 42.8 42.4 0.4 53 15 1952 1990 2020 2018 top-third 60 42.8 42.4 0.4 54 12 1953 1991 2020 2018 top-third 2003