MPA 12Z 500hPa temperature 1987 - - - - - - - - - - - -24.5 1988 -25.2 -19.2 -20.4 -25.0 -24.9 -28.2 -27.6 -31.6 -26.9 -28.8 -24.8 -23.6 1989 -22.1 -19.2 -21.5 -27.0 -26.1 -28.3 -25.1 -28.0 -28.5 -24.7 -23.5 -23.7 1990 - -18.0 -21.8 -28.6 -26.3 -27.2 -27.3 -30.0 -28.3 -27.0 -25.7 -23.8 1991 -19.2 -19.5 -21.3 -24.0 -27.4 -29.5 -29.0 -28.8 -27.5 -26.3 -25.7 -25.8 1992 -20.7 -21.8 -20.9 -21.1 -29.0 -31.8 -27.7 -28.7 -27.8 -27.8 -24.6 -23.7 1993 -25.6 -19.9 -21.6 -25.1 -25.6 -26.9 -29.9 -27.1 -27.4 -25.2 -24.0 -24.4 1994 -20.4 -24.4 -21.7 -25.3 -28.3 -28.4 -30.1 -27.7 -30.5 -28.4 -23.6 -22.7 1995 -21.0 -21.5 - -21.2 -26.7 -31.6 -33.1 -31.7 - -24.9 -25.1 -20.9 1996 -23.3 -21.7 -22.7 -24.1 -24.2 -28.9 -26.0 -27.7 -26.9 -27.4 -25.2 -22.9 1997 -20.9 -23.3 -19.6 -25.2 -26.0 -28.4 -32.3 -28.6 - - - - 1998 -23.1 -20.5 -22.7 -20.9 -25.3 -27.0 -29.4 -29.4 -29.8 -25.9 -24.1 -24.1 1999 -20.4 -22.3 -22.4 -22.1 -27.2 -29.8 -29.4 -27.3 -29.6 -25.5 -22.2 -23.6 2000 -21.6 -20.4 -22.2 -23.0 -25.3 -28.6 -30.4 -29.8 -31.4 -26.8 -26.8 -27.3 2001 -21.6 -23.7 -22.9 -24.1 -27.1 -29.5 -31.1 -26.0 -27.4 -23.2 -22.8 -21.6 2002 -20.9 -19.6 -25.1 -24.3 -28.5 -30.9 -28.5 -27.4 -29.2 -28.5 -27.5 -23.3 2003 -24.6 -21.0 -21.4 -23.8 -25.3 -29.9 -27.3 -28.0 -27.8 -26.8 -27.8 -25.0 2004 -20.6 -17.6 -20.4 -26.7 -26.2 -28.1 -28.8 -27.1 -29.5 -27.5 -24.1 -23.0 2005 -23.2 -18.3 -23.2 -25.1 -27.4 -30.2 -28.0 -29.1 -26.1 -28.1 -26.3 -24.8 2006 -20.9 -20.0 -21.5 -23.6 -23.1 -28.2 -29.7 -29.6 -29.6 -26.3 -25.4 -23.5 2007 -21.3 -23.2 -23.7 -28.1 -28.9 -29.9 -30.4 -29.5 -25.8 -27.7 -28.3 -22.8 2008 -21.7 -19.8 -19.5 -27.7 -26.9 -28.7 -29.8 -30.2 -26.9 -28.1 -25.7 -21.4 2009 - - - - - - - - - - - - 2010 - - - - - - - - - - - - 2011 - - -17.0 - - - - - - - - - 2012 - - - - - - - - - - - - 2013 - - - - - - - - - - - - 2014 - - - - - - - - - - - - 2015 - - - - - - - - - - - - 2016 - - - - - - - - - - - - 2017 - - - - - - - - - - - - 2018 - - - - - - - - - - - - 2019 - - - - - - - - - - - - 2020 - - - - - - - - - - - - 2021 - - - - - - - - - - - - 2022 - - - - - - - - - - - - 2023 - - - - - - - - - - - - 2024 - - - - - - - - - - - -