Ferrell 18Z temperature 1980 - - - - - - - - - - - - 1981 - -15.8 -21.2 -34.2 -31.1 -28.9 -33.1 -36.7 -38.8 -29.2 -18.8 -9.4 1982 -8.9 -16.2 -31.5 -35.3 -35.8 -35.6 -39.9 -31.5 -36.7 -28.5 -16.9 -8.0 1983 -9.5 -20.3 -24.9 -23.4 -25.0 -37.6 -36.5 - - - - - 1984 -10.4 -17.0 -23.7 -25.2 -28.9 -30.8 -35.5 -36.9 -34.9 - - - 1985 - -19.1 -24.4 -31.4 -30.8 - -43.5 -37.4 -34.3 -27.1 - - 1986 - -16.1 -24.2 -28.5 -24.9 -31.4 -34.6 -40.5 -43.5 -27.4 -16.3 -9.3 1987 - -17.3 -28.3 -32.1 -29.8 -27.9 -32.9 -35.3 -30.9 -27.6 -19.0 -7.6 1988 -9.4 -16.6 -27.9 -27.6 -28.3 -28.3 -34.7 -24.5 -27.4 -21.6 -16.7 -7.7 1989 -7.8 -17.8 -23.4 -25.1 - - - - - -23.6 -14.1 -7.8 1990 -9.3 -17.8 -27.2 -28.1 -29.6 -34.7 -34.3 -38.4 -39.0 -29.1 -17.0 -8.6 1991 -10.6 -13.5 -27.9 -28.4 -32.6 -27.6 - - - - -16.5 -8.3 1992 -9.2 -17.8 -21.0 -33.4 -29.3 -33.4 -30.7 - - - - - 1993 - -15.6 -25.8 -27.4 -34.7 -28.7 -31.5 -37.5 -33.3 -30.2 -15.2 -9.6 1994 -9.2 -18.0 -29.8 -24.7 -35.5 -32.1 -32.6 -37.3 -39.5 -24.1 -14.8 -7.9 1995 -9.2 -15.0 -27.9 -34.8 -34.6 -30.0 -36.1 -33.4 -34.0 -27.8 -15.3 -6.7 1996 -7.7 -16.7 -28.7 -25.1 -31.2 -31.9 -35.2 -29.0 -32.4 -28.5 -15.4 -7.3 1997 -8.5 -18.2 -29.2 -34.1 -30.2 -29.3 -35.6 -40.4 -31.0 -20.7 -10.9 -6.7 1998 -9.1 -12.2 -24.9 -36.3 -29.2 -24.6 -35.3 - - - - - 1999 - -16.2 - - - - - - - - - - 2000 - - - - - - - - - - - - 2001 - -14.4 -28.5 -27.8 -32.3 -27.3 -29.3 -42.0 -32.3 -26.9 -15.9 -7.1 2002 -7.3 -16.1 -21.4 -28.7 -26.8 -35.1 -38.2 -37.7 -28.3 -22.4 -14.1 -8.0 2003 -5.5 -14.4 -24.2 -31.3 -26.9 -28.5 -27.6 -37.6 -30.7 -21.8 -15.8 -7.1 2004 -8.0 - -29.3 -27.1 -33.4 -31.0 -41.9 -38.4 -34.8 -26.6 -12.8 -6.3 2005 -6.0 -15.7 -25.3 -28.9 -25.6 -31.2 -32.6 -33.1 -31.5 -23.0 -13.6 -4.5 2006 -7.4 -13.1 -23.8 -32.9 -35.5 -29.3 -37.4 -25.4 -28.3 -26.7 -14.4 -7.9 2007 -5.3 -13.8 -22.8 -28.2 -26.4 -28.1 -29.5 -30.1 -28.0 -27.0 -13.6 -6.2 2008 -6.1 -16.0 -22.3 -26.7 -29.7 -23.1 -34.0 -41.4 -25.0 -22.2 -16.8 -6.6 2009 -6.6 -17.5 -25.4 -23.0 -32.3 -30.3 -30.6 -34.4 -34.1 -26.6 -11.0 -5.1 2010 -6.4 -13.6 -22.9 -25.7 -32.3 -33.8 -35.5 -35.7 -34.8 -22.9 -14.1 -5.9 2011 -7.5 -16.5 -22.2 -26.9 -28.1 -26.9 -25.4 -28.5 -30.6 -24.0 -12.5 -5.5 2012 -6.0 -13.2 -22.6 -27.5 -23.7 -33.7 -34.1 -34.6 -29.3 -22.1 -14.8 - 2013 -7.5 -16.5 -21.8 -32.2 -27.9 -33.0 -35.3 -34.1 -28.2 -24.1 -17.0 -8.8 2014 - - -24.7 -30.5 -26.6 -34.0 -39.5 -24.7 - - - - 2015 - -12.7 -25.7 -33.1 -32.7 -31.9 -35.8 -33.6 -35.7 -25.3 -17.4 -9.0 2016 -6.9 -17.2 -24.1 -31.8 -30.6 -34.1 -37.6 -32.5 -33.2 -26.7 -15.7 -9.1 2017 -8.5 -17.2 -22.9 -24.4 -23.0 -30.3 -33.3 -29.2 -35.0 -23.8 -18.3 -9.6 2018 -8.9 -17.0 -21.7 -28.1 -30.8 -27.4 -33.4 -35.9 -32.2 -20.5 -14.7 -7.8 2019 -8.5 -13.9 -22.1 -29.1 -25.1 -31.2 -28.4 -28.8 -28.7 -24.6 -15.6 -7.1 2020 -8.4 -11.7 -25.1 -30.6 -27.6 -31.3 -31.2 -29.6 -32.0 -24.1 -18.6 -9.1 2021 -7.9 -16.8 -23.5 -36.0 -30.3 -31.9 -27.7 -39.9 -30.8 -25.3 -15.5 -8.5 2022 -9.5 -13.9 -23.5 -27.4 -23.6 -31.3 -29.1 -32.8 -31.4 -26.3 -20.3 -8.0 2023 -9.6 -16.0 -26.1 -30.3 -32.7 -28.1 -39.0 -42.2 -24.6 -26.9 -18.3 -9.2 2024 -8.6 - -26.3 -26.0 -31.0 -27.0 -33.6 -29.3 -34.3 -24.3 -18.8 -