SPI

干旱类别

0.5 ≤ SPI

湿润

−0.5 < SPI ≤ 0.5

正常

−1.0 < SPI ≤ −0.5

轻旱

−1.5 < SPI ≤ −1.0

中旱

−2.0 < SPI ≤ −1.5

重旱

SPI ≤ −2.0

特旱