Lettau 18Z temperature 1986 - -16.5 -29.0 -31.2 -25.1 -35.2 -39.7 -42.8 -47.2 -31.1 -15.8 - 1987 -6.4 -19.2 -35.3 -37.8 -35.8 -29.9 -34.5 -38.2 -37.7 -27.1 -19.3 -6.1 1988 -7.7 -17.6 -31.7 -31.2 -32.9 -34.3 -35.5 -27.1 -34.9 -23.5 - -7.2 1989 -7.1 -20.2 -28.2 -28.2 -35.4 -46.2 -37.0 -37.2 -34.9 -27.5 -14.2 -5.8 1990 -7.6 -19.0 -30.3 -31.6 -35.2 -34.8 -40.6 -40.3 -41.5 -29.9 -16.2 -5.5 1991 -8.7 -14.2 -31.7 -30.5 -32.9 -32.8 -39.6 - - - -15.1 -5.4 1992 -6.9 -18.5 -22.7 -37.9 -29.9 -35.3 - - - - -15.9 -6.6 1993 -7.8 -17.2 -30.6 -33.3 -40.8 - - - - - -16.7 -9.9 1994 -9.1 -18.9 -32.9 -27.3 -41.8 -35.3 -33.5 -41.2 -45.8 -24.9 -15.3 -5.6 1995 -8.4 -16.8 -29.1 -37.8 -40.2 -30.3 - - - - -14.3 -5.7 1996 -6.7 - - - - - - - - - - -5.5 1997 -7.4 - - - - - - - - - - - 1998 - - -29.8 -40.9 -33.9 - - - - - - - 1999 - -19.0 -33.1 -39.9 -39.6 -38.8 -32.9 -41.6 -29.3 -25.9 - - 2000 - - -25.0 -30.6 -34.2 -34.3 -32.7 -36.5 -35.4 -29.4 - - 2001 - - -31.8 -30.2 -37.4 -31.3 -31.3 -47.8 -35.6 -27.9 - - 2002 - - -22.3 -34.5 -27.7 -42.8 -43.0 -40.6 -31.0 -26.1 - - 2003 - - -28.4 -32.8 -30.9 -32.7 -33.1 -44.5 -36.6 -23.7 - - 2004 - - -32.2 -32.2 -39.6 -32.8 -47.8 -44.6 -40.9 -30.5 - - 2005 - -17.0 -27.8 -36.8 -29.1 -34.1 -32.1 -39.4 -35.8 -25.3 - - 2006 - - -29.8 -40.1 -44.6 -31.6 -40.8 -32.0 -33.2 -29.6 - - 2007 - - - - -33.8 -34.3 -34.7 -38.4 -35.9 -31.9 -16.2 -7.2 2008 -7.2 -19.0 -28.4 -32.2 -33.2 -31.2 -41.6 -49.6 - - - - 2009 - -22.9 -31.4 -28.4 -39.4 -42.8 -37.9 -41.3 -42.3 -29.4 -13.6 -7.5 2010 -10.7 -17.6 -31.3 -34.0 -40.0 -40.7 -42.3 -41.3 - - -15.4 -8.7 2011 -9.8 -19.8 -27.1 -31.8 -31.3 -32.7 - - - - - - 2012 - - - - - - - - - - - - 2013 - - - - - - - - - - - - 2014 - -16.9 -28.7 -38.7 -29.7 -41.5 -44.4 -28.6 -26.2 -22.0 -21.1 -10.6 2015 -9.3 -15.2 -27.7 -36.6 -34.2 -36.3 -40.9 -38.6 -39.1 -26.4 -17.4 -8.8 2016 -5.7 -18.5 -29.1 -36.0 -33.2 -41.0 -42.6 -37.7 -37.1 -28.0 -17.8 -9.0 2017 -9.0 -18.1 -28.2 -23.5 -25.7 -35.1 -39.9 -30.5 -41.9 -27.5 -19.6 -10.7 2018 -9.8 -19.2 -24.6 -30.5 -35.1 -34.4 -37.2 -44.5 -34.8 -23.7 -14.2 -7.2 2019 -9.7 -15.6 -28.0 -32.3 -31.8 -33.6 -34.4 -33.1 -28.4 -26.2 -16.1 -7.3 2020 -10.1 -14.2 -28.8 -32.6 -31.8 -34.7 -36.9 -36.5 -36.2 -24.6 -20.1 -9.1 2021 -9.2 -19.0 -32.5 -40.5 -35.0 -33.4 -33.7 -49.8 -36.2 -27.6 -15.7 -7.8 2022 -9.0 -15.0 -27.5 -31.6 -28.4 -37.2 -28.3 -35.7 -35.5 -29.2 -21.9 -7.8 2023 -9.8 -18.0 -29.9 -35.6 -39.1 -31.2 -45.6 -47.6 -24.7 -29.2 -18.6 -9.6 2024 -8.4 -19.2 -25.3 -29.2 -32.9 -31.8 -36.3 -35.5 -40.6 - -18.9 -