The U.S. Drought Monitor (2000–present) depicts the location and intensity of drought across the country. Every Thursday, authors from NOAA, USDA, and the National Drought Mitigation Center produce a new map based on their assessments of the best available data and input from local observers. The map uses five categories: Abnormally Dry (D0), showing areas that may be going into or are coming out of drought, and four levels of drought (D1–D4). Learn more.
Drought results from an imbalance between water supply and water demand. The Standardized Precipitation Index (SPI) measures water supply, specifically precipitation. SPI captures how observed precipitation (rain, hail, snow) deviates from the climatological average over a given time period—in this case, over the 9 months leading up to the selected date. Red hues indicate drier conditions, while blue hues indicate wetter conditions. Data are available monthly from 1895–present. Learn more.
In paleoclimatology, proxy climate data (e.g., tree rings, ocean sediments) can allow us to reconstruct past climate conditions before we had widespread instrumental records. The Living Blended Drought Atlas, shown here, estimates average drought conditions each summer (June–August) as far back as the year 0 by combining tree-ring reconstructions and instrumental records. Red hues indicate drier conditions, while blue hues indicate wetter conditions.