Drought category | Classification | Value |
D0 | Abnormally dry | −0.5 to −0.7 |
D1 | Moderate drought | −0.8 to −1.2 |
D2 | Severe drought | −1.3 to −1.5 |
D3 | Extreme drought | −1.6 to −1.9 |
D4 | Exceptional drought | −2.0 or less |