Clean_Air 18Z temperature 1986 - -36.2 -53.6 -55.6 -62.2 -64.1 -60.3 -59.6 - - -38.4 -28.8 1987 -27.6 -41.7 -52.4 -60.3 -60.3 -58.5 - - - - -41.0 -28.9 1988 -28.2 -43.4 -50.3 -60.2 -62.4 -59.3 -63.2 -58.8 -58.0 -50.2 -38.6 -29.9 1989 -30.7 -41.9 -55.4 -62.3 -63.2 -64.8 -59.2 -56.7 -59.1 -53.1 -38.0 -26.2 1990 -27.9 -42.2 -56.4 -60.8 -62.8 -58.0 -59.3 -63.4 - - - -25.5 1991 -28.7 -38.2 -57.5 -60.3 -61.0 -60.3 -58.5 -60.6 -54.3 -52.2 -39.1 -26.5 1992 -29.9 -44.1 -58.5 -54.8 -61.0 -57.4 -61.9 -63.0 -59.7 -47.8 -39.1 -29.8 1993 -29.0 -43.4 -54.5 -60.6 -59.0 -63.3 -59.2 -66.8 -60.3 - - - 1994 - -43.8 -54.4 -58.2 -59.9 -56.3 -62.7 -59.2 -58.6 -51.2 -36.5 -27.8 1995 -30.2 -40.4 -53.3 -59.8 -60.3 -59.3 -56.8 -63.3 -65.0 -48.5 -37.0 -26.0 1996 -28.0 -37.1 -57.3 -56.0 -61.0 -60.6 -57.4 -54.3 -60.5 -52.3 -34.5 -24.9 1997 -28.4 -43.5 -56.3 -56.5 -58.5 -58.4 -66.2 -60.4 -61.1 -52.9 -33.0 -26.3 1998 -26.3 -38.6 -53.2 -63.3 -59.0 -56.6 -59.6 -63.8 -63.2 -53.9 -36.4 -26.8 1999 -24.7 -40.6 -54.5 -62.0 -58.0 -60.0 -63.7 -58.5 -63.0 -50.1 -37.9 -29.0 2000 -28.7 -42.2 -55.3 -62.4 -59.8 -60.0 -61.1 -60.4 -61.5 -50.0 -32.8 -26.0 2001 -27.5 -38.3 -56.2 -60.6 -59.0 -58.2 -61.5 -64.5 -57.2 -50.7 -34.0 -25.2 2002 -25.1 -40.5 -51.2 -53.6 -57.2 -63.0 -54.1 -59.0 -57.1 -45.4 -37.2 -28.6 2003 -25.7 -37.9 -52.0 -55.0 -57.7 -63.0 -62.6 -54.6 -59.8 -48.0 -34.4 -21.5 2004 -24.0 -35.7 -52.7 -53.1 -56.1 -60.2 -65.9 -60.1 -52.6 -45.9 -35.0 -21.6 2005 - - - - - - - - - - - - 2006 - - - - - - - - - - - - 2007 - - - - - - - - - - - - 2008 - - - - - - - - - - - - 2009 - - - - - - - - - - - - 2010 - - - - - - - - - - - - 2011 - - - - - - - - - - - - 2012 - - - - - - - - - - - - 2013 - - - - - - - - - - - - 2014 - - - - - - - - - - - - 2015 - - - - - - - - - - - - 2016 - - - - - - - - - - - - 2017 - - - - - - - - - - - - 2018 - - - - - - - - - - - - 2019 - - - - - - - - - - - - 2020 - - - - - - - - - - - - 2021 - - - - - - - - - - - - 2022 - - - - - - - - - - - - 2023 - - - - - - - - - - - - 2024 - - - - - - - - - - - -