MPA 00Z 500hPa temperature 1987 - - - - - - - - - - - -25.6 1988 -24.4 -18.8 -18.5 -24.7 -25.1 -27.2 -27.5 -31.5 -27.6 -28.5 -24.8 -24.2 1989 -21.9 -18.9 -20.5 -26.5 -27.7 -27.6 -25.1 -27.7 -28.8 -25.0 -22.4 -23.0 1990 - -18.1 -21.9 -28.4 -26.0 -28.4 -26.1 -29.5 -28.7 -27.0 -26.3 -24.3 1991 -19.1 -20.3 -21.0 -24.4 -26.9 -29.9 -27.8 -28.4 -26.6 -27.6 -24.9 -24.7 1992 -19.4 -22.0 -20.9 -20.7 -28.9 -30.9 -28.7 -29.1 -27.8 -27.1 -24.8 -22.8 1993 -25.7 -19.2 -21.2 -25.0 -26.0 -26.3 -30.3 -27.8 -27.3 -24.8 -24.5 -24.4 1994 -20.2 -23.3 -21.5 -24.9 -27.9 -27.8 -29.0 -27.9 -29.9 -27.9 -24.2 -23.1 1995 -21.0 -21.7 - -21.2 -26.4 -31.7 -33.9 -32.8 - -24.4 -24.9 -21.3 1996 -22.5 -20.9 -21.1 -23.7 -23.8 -29.2 -26.9 -27.8 -26.8 -26.8 -25.2 -23.0 1997 -20.5 -23.0 -19.2 -24.5 -25.6 -28.0 -30.2 -30.0 - - - - 1998 -23.8 -20.6 -21.8 -21.6 -25.4 -27.0 -28.8 -29.8 -30.6 -26.3 -24.5 -23.8 1999 -20.4 -22.2 -21.7 -21.1 -27.0 -29.8 -29.0 -27.6 -28.8 -25.6 -21.8 -21.9 2000 -21.1 -20.4 -20.8 -23.5 -24.5 -27.8 -29.3 -29.8 -31.4 -27.9 -27.3 -26.7 2001 -22.3 -22.9 -22.8 -24.5 -26.4 -29.1 -31.0 -26.6 -27.6 -22.6 -22.9 -21.2 2002 -20.8 -18.9 -25.0 -22.9 -28.7 -30.2 -28.1 -27.4 -29.0 -28.8 -27.6 -22.4 2003 -23.6 -19.5 -21.9 -23.7 -25.0 -30.2 -26.7 -27.7 -27.3 -26.3 -27.8 -24.7 2004 -18.9 -17.3 -20.4 -26.5 -26.4 -27.5 -28.6 -27.8 -29.4 -26.7 -24.3 -23.2 2005 -22.8 -17.6 -22.6 -24.1 -27.2 -30.2 -28.0 -29.1 -26.7 -28.2 -26.5 -24.1 2006 -20.6 -19.6 -20.9 -23.7 -23.5 -28.4 -29.4 -29.6 -29.7 -25.0 -25.8 -22.8 2007 -21.1 -23.0 -22.7 -28.1 -27.8 - - - -26.0 -26.7 -28.4 -21.7 2008 -21.3 -19.4 -19.6 -27.6 -27.4 -28.7 -29.8 -30.7 -26.5 -26.4 -27.3 -20.6 2009 -21.5 -21.0 -22.1 -26.0 -28.6 -26.4 -29.2 -30.4 -27.7 -27.5 -28.9 -24.1 2010 -22.1 -22.4 -20.7 -24.3 -25.6 -27.7 -28.8 -28.8 -28.5 -24.7 -23.5 -24.5 2011 -19.6 -17.9 -20.9 -25.0 -25.4 -28.0 -29.4 -31.3 -29.1 -27.0 -23.2 -19.7 2012 -19.0 -24.1 -21.9 -25.8 -27.5 -30.7 -31.8 -25.1 -28.1 -27.5 -24.5 -25.2 2013 -19.8 -21.4 -20.4 -20.1 -26.8 -28.3 -27.8 -31.0 -27.7 -25.9 -25.5 -25.7 2014 -23.7 -21.0 -22.7 -23.1 -26.9 -26.4 -28.3 -28.0 -26.6 -26.6 -24.7 -24.2 2015 -22.3 -21.0 -21.2 -24.1 -24.9 -29.0 -29.5 -29.4 -30.4 -26.7 -24.4 -24.9 2016 -21.7 -20.8 -19.0 -24.9 -24.6 -24.8 -29.9 -28.9 -25.2 -25.0 -24.8 -23.5 2017 -22.5 -18.5 -20.6 -23.3 -23.2 -31.0 -28.8 -28.7 -27.5 -27.2 -23.0 -23.4 2018 -20.7 -18.1 -21.6 -25.3 -26.6 -29.2 -28.5 -27.9 -27.7 -27.2 -24.4 -20.1 2019 -23.3 -21.7 -20.6 -24.4 -26.4 -27.4 -28.8 -30.3 -29.5 -26.6 -25.5 -23.7 2020 -21.6 -20.0 -19.1 -22.4 -25.6 -29.0 -31.0 -30.1 -27.4 -23.7 -21.2 -21.2 2021 - -16.6 -19.8 -20.4 -27.3 -27.2 -29.7 -27.8 -25.4 -25.8 -23.9 -18.7 2022 -20.2 -20.1 - -24.5 -26.0 -27.2 -29.7 -29.0 -25.5 -24.0 -21.0 -21.3 2023 -18.5 -20.5 -22.2 -24.6 -25.4 -27.6 -30.0 -29.9 -28.6 -26.0 -24.1 -22.0 2024 -19.0 -17.3 -23.9 -23.2 - - - - - - - -