Agricultural drought results from below-normal precipitation and/or above-normal temperatures/wind that evaporate moisture from soils and plants. The location, extent, and severity of drought impacts to agriculture depend on underlying social and ecosystem vulnerabilities, access to irrigation, types of crops grown, and other factors.

Drought can be a contributing factor to wildfire. Dry, hot, and windy weather combined with dried out (and more flammable) vegetation can increase the probability of large-scale wildfires.

Monitoring the climate at various timescales allows identification of short-term wet periods within long-term droughts or short-term dry spells within long-term wet periods. Indices can simplify complex relationships and provide useful communication tools for diverse audiences and users, including the public. [ Reference: WMO Handbook on Indicators and Indices ]

Paleoclimatologists study environmental evidence to understand what the Earth’s past climate was like and why. They use proxy climate records to estimate past conditions and extend our understanding of climate that existed long ago.

Some health effects of drought are easy to observe and measure, but drought’s slow rise can result in indirect health implications that are more difficult to recognize.

Snowpack typically acts as a natural reservoir, providing water throughout the drier summer months. Lack of snowpack storage, or a shift in timing of snowmelt from that reservoir, can be a challenge for drought planning. Snow drought is a period of abnormally little snowpack for the time of year. Recent research shows that the western U.S. has emerged as a global snow drought “hotspot,” where snow droughts became more prevalent, intensified, and lengthened in the second half of the period 1980 to 2018.Read the Latest Snow Drought Update

Soil moisture plays an important role in agricultural monitoring, drought and flood forecasting, forest fire prediction, water supply management, and other natural resource activities. Soil moisture observations can forewarn of impending drought or flood conditions before other more standard indicators are triggered.

Air temperature and precipitation can have wide-ranging effects on natural processes, and their datasets are foundational for drought and climate analysis. Changes in temperature and precipitation can substantially disrupt crops and livestock, influence the frequency and intensity of severe weather events, and affect the quality and quantity of water available for municipal and industrial use. 

Vegetation refers to plant life, including agricultural and developed vegetation, desert and semi-desert, forest, shrubs, herbs, and natural land cover. Drought can result in reduced growth rates, increased stress on vegetation, and alterations or transformations to the plant community and/or the entire ecosystem.

When drought impacts affect the water supply—the water levels in streams, reservoirs, and groundwater—it is known as hydrological drought. Periods of drought can lead to inadequate water supply, threatening the health, safety, and welfare of communities.