SPI classes | Degree of drought | Concerned year |
SPI > 2 | Extreme humidity | 2012, 2016 |
1 < SPI < 2 | Hight humidity | 2017, 2009, 2015, 1991 |
0 < SPI < 1 | Moderate humidity | 2003, 2014, 2005, 2010, 1999, 1989, 2013, 1987, 2004, 2008, 1978, 1993 |
0 < SPI < −1 | Moderate drought | 1988, 1979, 1994, 1981, 2007, 1995, 1992, 2011, 1996, 1990, 1983, 1984, 1986, 1998, 2002, 1977, 1982 |
−1 < SPI < −2 | Severe drought | 2001, 2006, 2000, 1980, 1997, 1985 |
SPI < −2 | Extreme drought | - |