Priestley_Gl 18Z temperature 1987 - - -22.5 - - - - - - -23.3 -18.4 -9.3 1988 -9.5 -16.5 - - - - - - - - - -10.2 1989 - -17.3 -24.4 -25.3 -30.7 -34.8 -29.1 -32.6 -27.0 -25.8 -17.0 -8.7 1990 -9.8 -17.1 -24.6 -29.5 -28.2 -29.5 -24.3 -32.0 -30.0 -25.5 -15.4 -8.1 1991 -9.7 -14.4 -24.6 -25.5 - - - - -27.7 - - -7.2 1992 -10.0 -15.9 -22.7 -28.5 -27.9 -26.5 -28.2 -23.5 -32.0 -25.8 - -10.3 1993 - -16.5 -23.1 -28.2 -31.5 -30.2 -28.9 -30.7 -27.1 -25.1 -16.5 -10.4 1994 -9.1 -18.0 -27.5 -25.7 -31.7 -30.7 -27.0 - - - - -10.1 1995 -11.1 - -22.5 -25.5 -28.9 -29.2 -28.9 -27.4 -28.5 -25.9 -17.7 - 1996 -9.9 -15.8 -20.4 -24.7 -31.1 -31.0 -30.0 -26.0 -30.3 -27.9 - -8.6 1997 -9.9 -17.0 -23.8 -30.1 -31.7 - - - - - - -11.1 1998 -11.5 -16.1 -26.4 -29.0 -29.5 -28.9 -31.9 -29.6 -29.4 -25.1 -18.5 -9.6 1999 -9.2 -16.4 -24.7 -28.8 -31.2 - - - - - -15.6 -10.6 2000 -10.9 -17.4 -24.3 -29.6 -27.6 -29.4 -29.2 -29.9 -24.5 - - -10.2 2001 -10.1 -15.7 -24.4 -28.4 -29.6 -28.8 -30.0 -31.7 -29.7 -26.2 -16.9 -8.9 2002 -6.9 -16.8 -22.1 -29.2 -27.3 -25.5 -31.1 -34.6 -27.1 -24.1 -16.9 -9.5 2003 -8.1 -16.4 -25.1 -29.0 -27.4 -29.9 - - - - -16.3 -8.6 2004 -9.4 -14.7 -23.0 -27.6 -31.0 -24.5 -34.1 -29.0 -28.3 -26.1 -16.2 -7.3 2005 -9.2 -16.2 -23.6 -30.0 - -27.5 - - - - -15.4 -6.9 2006 -8.7 -16.1 -24.5 -27.9 -28.8 -29.0 -31.7 -29.2 -29.4 - - -12.3 2007 -8.6 -18.8 -24.6 -28.9 -28.2 -31.3 -31.8 -34.5 -32.8 -26.0 -18.1 -11.1 2008 - - - - - - - - - - -18.1 -10.6 2009 -10.3 -19.0 -26.7 -31.3 -29.7 -30.4 -28.2 - - - - -10.4 2010 -9.1 -16.4 -22.6 -30.9 -32.4 -35.1 -36.6 -32.6 -33.8 -28.1 - - 2011 - - - - - - - - - - - -9.8 2012 -10.2 - - - - - - - - - - -9.2 2013 -10.6 -19.5 -26.4 -32.1 -31.2 -31.8 - - - -27.1 -19.7 -9.5 2014 - - - - - - - - - - - -11.8 2015 -11.0 -17.8 -25.4 -32.3 -31.0 -33.1 - - - -25.9 -20.9 -10.5 2016 -10.8 -18.6 -27.0 -33.1 -28.5 -32.9 - - - -28.7 -15.1 -10.9 2017 -10.2 -17.5 -25.0 -31.0 -31.2 -33.0 - - - -25.3 -18.6 -11.4 2018 -11.0 -18.4 -24.8 -27.0 -33.8 -32.5 - - - -25.2 -18.9 -11.2 2019 -11.8 -18.7 -24.4 -30.3 -30.0 -33.7 - - - -28.6 -16.5 -10.2 2020 -10.2 -15.4 -25.1 -30.1 -32.8 -33.4 - - - -30.0 -20.4 -11.0 2021 -11.3 -19.1 -25.8 -32.3 -36.0 - - - - -26.3 -19.3 -11.2 2022 -12.1 -17.2 -23.3 -30.8 -30.2 -29.2 - - - - - - 2023 -12.4 -18.3 -24.7 -28.0 -32.2 -30.9 -31.0 -33.6 -29.6 -30.5 -19.6 -11.3 2024 -11.9 -19.6 -26.8 -32.3 -32.7 -33.3 -29.1 -30.6 -30.5 -27.6 -21.2 -10.0 2025 -9.7 -17.0 -26.7 -29.8 -30.8 -28.0 -30.6 -31.4 -30.0 -24.7 - - 2026 - - - - - - - - - - - -