October 2012

Drought is a deficiency in precipitation over an extended period. It is a normal, recurrent feature of climate that occurs in virtually 

all climate zones. The duration of droughts varies widely. There are cases when drought develops relatively quickly and lasts a very 

short period of time, exacerbated by extreme heat and/or wind, and there are other cases when drought spans multiple years, or 

even decades. Studying the paleoclimate record is often helpful in identifying when long-lasting droughts have occurred.

What is Drought?

The U.S. Drought Monitor (USDM) is a weekly product that 

provides a general summary of current drought conditions. 

Multiple drought indicators, including various indices, outlooks, 

field reports, and news accounts are reviewed and synthesized. 

In addition, numerous experts from agencies and offices 

across the country are consulted. The result is the consensus 

assessment presented on the USDM map.

http://droughtmonitor.unl.edu http://drought.unl.edu

How is Drought Monitored and Assessed?

www.drought.gov

The USDM is an integral monitoring component in the National 

Integrated Drought Information System (NIDIS), which was 

established by Congressional Act in 2006 to implement an 

integrated drought monitoring and forecasting system at federal, 

state, and local levels. NIDIS includes drought monitoring, 

forecasting, response, research, and education components 

as part of its early warning system. These components are 

featured within the U.S. Drought Portal.

www.drought.gov

For drought monitoring, forecasting, 

and information go to:

Drought Impact Reporter: The goal of the National Drought 

Mitigation Center’s Drought Impact Reporter is to collect, 

quantify, and map reported drought impacts for the United 

States and provide access to the reports through interactive 

search tools. Users can submit their own drought impact 

reports through the tool’s easy web interface.

droughtreporter.unl.edu
Socioeconomic Drought

Socioeconomic drought is based on the impact of 

drought conditions (meteorological, agricultural, 

or hydrological drought) on supply and demand 

of some economic goods. Socioeconomic drought 

occurs when the demand for an economic good 

exceeds supply as a result of a weather-related 

deficit in water supply. 

Meteorological Drought

Meteorological Drought is based on the degree 

of dryness (rainfall deficit) and the length of 

the dry period.

Agricultural Drought

Agricultural Drought is based on the impacts to agriculture by 

factors such as rainfall deficits, soil water deficits, reduced ground 

water, or reservoir levels needed for irrigation.

Hydrological Drought

Hydrological Drought is based on the impact of rainfall deficits 

on the water supply such as stream flow, reservoir and lake 

levels, and ground water table decline.

Common Types of Drought

Why is Drought Important?

The United States is vulnerable to the social, economic, and 

environmental impacts of drought. More than 100 years of U.S. 

weather records indicate that there have been three or four major 

drought events during that period. Two of these, the 1930s Dust 

Bowl drought and the 1950s drought, each lasted five to seven 

years and covered large areas of the continental United States.

Droughts are among the most costly weather related events.

According to the National Climatic Data Center (NCDC), the United 

States has sustained 114 weather/climate disasters over the past 

31+ years (up to 2011) in which overall damages/costs reached 

or exceeded $1 billion. The total standardized losses for the 114 

events exceed $800 billion.

During this period, there have been 16 billion-dollar droughts, 

totaling $195 billion in losses, which amounts to approximately 

$12 billion for each billion-dollar drought event that has occurred. 

Billion Dollar Drought and Heat Wave Disasters

1980-2011

Human factors, such as water demand and water management, 

can exacerbate the impact that drought has on a region. 

Because of the interplay between a natural drought event 

and various human factors, drought means different things to 

different people. In practice, drought is defined in a number of 

ways that reflect various perspectives and interests.

www.cpc.ncep.noaa.gov/products/expert_assessment/seasonal_drought.html

Additional information can be found at: www.drought.unl.edu/DroughtBasics/TypesofDrought.aspx

The U.S. Seasonal Drought Outlook shows predicted trends 

for areas experiencing drought depicted in the U.S. Drought 

Monitor, as well as indicating areas where new droughts may 

develop. The NOAA Climate Prediction Center issues this monthly 

product in conjunction with their long-lead temperature and 

precipitation outlooks on the first and third Thursday of each 

month and when weather events warrant an interim update. 

The general large-scale trends depicted are based on numerous 

indicators, including short and long-range forecasts. A discussion 

detailing the atmospheric, hydrologic, and climatic conditions 

affecting the drought trends is included.

Source: National Climatic Data Center