SPI values | Classes |
>2 | Extremely wet |
1.5 to 1.99 | Very wet |
1.0 to 1.49 | Moderately wet |
−0.99 to 0.99 | Near normal |
−1 to ?1.49 | Moderately dry |
−1.5 to −1.99 | Severely dry |
<−2 | Extremely dry |