The U.S. Drought Monitor map provides a summary of drought conditions across the United States and Puerto Rico. Often described as a blend of art and science, the map is updated weekly by combining a variety of data-based drought indices and indicators and local expert input into a single composite drought indicator.
The map denotes four levels of drought intensity (ranging from D1 - D4) and one level of "abnormal dryness" (D0). Also depicted are areas experiencing agricultural (A) or hydrological (H) drought impacts. These impact indicators help communicate whether short- or long-term precipitation deficits are occurring.
History Behind the Drought Monitor
Prior to launching the U.S. Drought Monitor, drought experts had realized the need for a simple, accurate way to communicate drought conditions to decision makers and the public. The map was designed to show drought intensity on a scale similar to tornadoes and hurricanes, which is already well known to many people. The U.S. Drought Monitor map was unveiled in August 1999 at a White House press conference. The map has been produced every week for over 10 years, and on April 7, 2009 the U.S. Drought Monitor hit a milestone with its 500th map.
Who Uses the Drought Monitor?
The U.S. Drought Monitor sets the standard for communicating location and intensity of drought to a broad audience. The map summarizes and synthesizes information from the local and state level to the national scale, making it the most widely used gauge of drought conditions in the country. Policy makers use it to allocate relief dollars, states use it to trigger drought response measures, and media rely on it. The USDA uses it to distribute millions, even billions, of dollars in drought relief to farmers and ranchers each year, and the Internal Revenue Service also uses it for ranching-related tax determinations.