Monitoring Drought in the United States: Status and Trends - Monitoring and Predicting Agricultural Drought: A Global Study - page 128

Table 9.2 Drought Monitor's drought severity classification system

Drought type Associated ranges of objective indicators

CPC soil USGS

Palmer moisture weekly Percent Standardized Satellite

drought model streamflow of normal precipitation vegetation

Category Description index (percentiles) (percentiles) precipitation index health index

D0 Abnormally dry -1.0 to -1.9 21-30 21-30 < 75% for 3 months -0.5 to -0.7 36-45

D1 Moderate drought -2.0 to -2.9 11-20 11-20 < 70% for 3 months -0.8 to -1.2 26-35

D2 Severe drought -3.0 to -3.9 6-10 6-10 < 65% for 6 months -1.3 to -1.5 16-25

D3 Extreme drought -4.0 to -4.9 3-5 3-5 < 60% for 6 months -1.6 to -1.9 6-15

D4 Exceptional drought -5.0 or less 0-2 0-2 < 65% for 12 months -2.0 or less 1—5