A drought is a period of abnormally dry weather characterized by a prolonged deficiency of precipitation below a certain threshold over a large area and a period longer than a month (WMO, 2020).

It is a weather-related natural hazard, which can affect vast regions for months or years, significantly impacting economic performance, particularly food production. Millions of people are affected by droughts each year and it is expected that vulnerability to drought will increase due to population increases, environmental degradation, development pressures and climate change.

There is little, if anything, that can be done to alter the occurrence of droughts. However, it is important that scientists try to understand and communicate the probability of drought events of various levels of intensity and duration. The World Meteorological Organization (WMO) has adopted the Standardized Precipitation Index (SPI) as a global standard to measure meteorological droughts on the basis of rainfall data.

The Integrated Drought Management Programme (IDMP), co-sponsored by the WMO and the Global Partnership Water (GWP), have developed a three pillar approach to Integrated Drought Management. These pillars include: drought monitoring and early warning; drought vulnerability and impact assessment; and drought mitigation, preparedness and response. IDMP developed the National Drought Management Policy Guidelines, which include a 10-step process to assist countries in developing national drought plans and policies (WMO and GWP, 2014).

Drought types

Meteorological drought: Occurs when dry weather patterns dominate an area. It is defined usually on the basis to the degree of dryness and the duration of the dry period.

Agricultural drought: Occurs when agricultural production becomes affected. It focuses on precipitation shortages, differences between actual evapotranspiration, soil water deficits, reduced groundwater and so on.

Hydrological drought: Occurs when low water supply becomes evident and is associated with the effects of periods of precipitation shortfalls on surface or subsurface water supply.

Socio-economic drought: Relates to the supply and demand of some economic goods with elements of meteorological, hydrological, and agricultural drought. It also occurs when the demand for an economic good exceeds supply as a result of a weather-related shortfall in water supply.

Drought risk factors

Drought risks are associated with:

  • Deficient or erratic rainfall. 
  • Poverty and rural vulnerability.
  • Poor water and soil management.
  • Weak or ineffective governance.
  • Climate change.

Vulnerable areas

Droughts affect all climactic regions, but parts of Africa are among the most vulnerable. 

  • For example, in the African Sahel, warmer and drier conditions have led to a reduced growing season with detrimental effects on crops. 
  • In southern Africa, longer dry seasons and more uncertain rainfall are prompting adaptation measures.
  • Poor rural households, whose livelihoods depend on rain-fed subsistence agriculture, are the social groups most exposed and vulnerable to drought.
  • Droughts are rarely, or solely, responsible for conflicts, but they can contribute to the likelihood of conflict by increasing competition for scarce resources and by exacerbating ethnic tensions, usually due to displacement or migration.

Risk reduction measures

  • Policy and governance, political commitment for drought risk management.
  • Drought risk identification, impact assessment and early warning, including hazard monitoring and analysis.
  • Design and implementation of anticipatory actions to mitigate the impact of drought before it occurs to reduce the need for humanitarian assistance.
  • Drought awareness and knowledge management to create the basis for a culture of drought risk reduction and resilient communities.
  • Development of water-saving practices and policies to promote and enforce sustainable land and water management.
  • All of these elements need strong political commitment, community participation, and consideration of local realities and indigenous knowledge.

Latest Drought additions in the Knowledge Base

A family fetches water from a stream during a drought in Madagascar
Research briefs
Researchers have proposed deep learning models that predict droughts using climate data. Long-term forecasts of this kind are sought by agricultural producers planning their operations, by insurance companies and banks evaluating climate risks.
Skoltech - Skolkovo Institute of Science and Technology
Small boats stranded in the nearly dry bed of the Tapajos river in Alter do Chao, Santarem, Brazil, during the amazonian drought in the second half of 2023
Research briefs
Severe droughts in the Amazon basin over the past two decades have caused low water level periods to last around a month longer than usual, triggering profound impacts on the local population.
Escola de Prevenció i Seguretat Integral - Universitat Autònoma de Barcelona
Research briefs
Researchers from around the world to examine what factors play a role in creating flash drought conditions. While their study used South Asia as a model, the findings can be applied to Texas and other areas that experience flash droughts.
Texas A&M University Press
Afghan men construct a wall
UNDP, with funding from the Special Trust Fund for Afghanistan (STFA), implemented several projects aimed at increasing the resilience of communities on preventing flash floods and training locals for disaster risk preparedness, response, and recovery.
United Nations Development Programme - Afghanistan
According to data from Brazil's National Institute for Space Research, the Amazon saw 13,489 wildfires in the first half of the year — up more than 61% compared to the same period last year.
Deutsche Welle
The desert is encroaching across Sicily, the largest and most populous island in the Mediterranean, where a European temperature high of 48.8C was recorded in 2021. Rainfall is down by more than 40% since 2003.
Guardian, the (UK)
A child drinks water in Mali, Kenya
UNESCO's CARE4WATER initiative aims to boost climate resilience and secure water resources in East Africa by integrating science, socio-economic insights, and community empowerment.
United Nations Educational, Scientific and Cultural Organization - Headquarters
Documents and publications
This study evaluates the impact of sand dams on resilience to climate variability and changes through a participatory case study approach in the Shashe catchment, a semi-arid catchment shared by Botswana and Zimbabwe.
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