NOAA's National Centers for Environmental Information
Index
- Alaska Climate Divisions FAQs
- Anomalies vs. Temperature
- Arctic Sea Ice Measurements
- Billion-Dollar Disasters: Calculating the Costs
- Binomial Filter
- Climate Division Dataset Transition
- Climate Extremes Index
- CLIMAT Messages
- Climatological Rankings
- Coral Reef Bleaching
- Dead Fuel Moisture
- Definition of Drought
- Drought Indicators
- Drought in the Colorado River Basin
- Drought vs. Aridity
- El Niño: A Historical Perspective
- Explanation of the 500 mb Flow
- Future Drought
- Global Precipitation Percentile Maps
- Global Regions Definitions
- Global Temperature Anomaly Percentile Maps
- Global Temperature Uncertainty
- Groundwater Drought Indicators
- Hawaiʻi Climate Divisions FAQs
- LOESS
- Measuring Drought
- Monthly Releases
- Monthly Report RSS Feed
- nClimDiv Maximum and Minimum Temperatures
- Palmer Drought Index
- Potential Evapotranspiration
- Reforestation of Bastrop Lost Pines
- Regional Climate Centers
- Regional Snowfall Index (RSI)
- Satellite-Based Drought Indicators
- Soil Moisture Water Balance Models
- Southern Hemisphere Snow Cover Extent
- Standardized Precipitation Index
- Streamflow Drought Indicators
- Subtropical Highs
- Tornado Count
- U.S. Climate Divisions
- U.S. Climate Normals
- U.S. Drought Monitor Scale
- USHCN Version 2.5 Transition
- Water Supply vs. Water Demand
U.S. Drought Monitor Scale
The U.S. Drought Monitor (USDM) established a drought scale much like those that rate hurricanes and tornadoes. The "D-scale" speaks to the "unusualness" of a drought episode. Over the long run, D1 conditions are expected to occur about 10 to 20 percent of the time. D4 is much rarer, expected less than 2 percent of the time. For more detailed information about drought definitions, please visit the U.S. Drought Monitor.
