The U.S. Drought Monitor is a weekly assessment of the extent and severity of drought in the United States.
Objective blends combine different gridded datasets into a single map, weighted to account for differences in the eastern and western parts of the country. The blends are combinations of the Standardized Precipitation Index, the Standardized Precipitation and Evapotranspiration Index, and soil moisture data.
The Drought Impact Toolkit is a collection of tools for monitoring drought impacts, based on news, social media, crowdsourcing and citizen science, as well as links to other tools and places to look for drought impacts. It also has a collection of post-drought assessments, mostly by different state agencies, that examine how past droughts have affected people, livelihoods and the environment.
The Drought Impact Reporter is a historic archive of the effects of drought, based mainly on media reports and volunteers’ observations. It’s a good starting point if you want to see how drought has affected people’s livelihoods and the environment in your area since 2005.
The North American Drought Monitor, produced monthly, shows the area and intensity of drought.
We overlay the U.S. Drought Monitor on agricultural census data to determine what proportion of different crop-producing areas are affected by drought.
Managing Drought Risk on the Ranch includes a drought monitoring dashboard that incorporates the U.S. Drought Monitor, precipitation, outlooks, grassland productivity forecasts (Grass-Cast), and vegetation drought stress (VegDRI).
For a list of the pros and cons of 50 different drought indicators in use around the world, please refer to the Handbook of Drought Indicators and Indices. It was developed by Mark Svoboda and Brian Fuchs of the National Drought Mitigation Center at the University of Nebraska-Lincoln, and published in 2016 by the World Meteorological Organization and the Global Water Partnership. A PDF version is also available.
The Drought Risk Atlas provides a historic look at drought for a specific location, going back as far as we have good data. See or download precipitation, temperature, or several different drought indices, including the U.S. Drought Monitor, the Standardized Precipitation Index and the Palmer Drought Severity Index.
The Palmer Drought Severity index has been calculated by climate division for several time periods starting in 1895.
Select a river basin to view a graph of the Palmer Drought Severity Index from 1895 to 2004.
The Vegetation Drought Response Index combines data from satellites with ground-based measurements and other information to detect drought’s effects on vegetation.
The Quick Drought Response Index detects “flash drought,” when heat and dryness combine to change environmental conditions over a few days or a few weeks.
Grass-Cast uses almost 40 years of historical data on weather and vegetation growth— combined with seasonal precipitation forecasts—to predict whether rangelands in individual grid cells (whose size is 10 x 10 kilometers, or about 6 x 6 miles) are likely to produce above-normal, near-normal, or below-normal amounts of vegetation.
NASA’s GRACE satellite mission provides data on how much water is beneath the Earth’s surface. We use it to map soil moisture, root zone moisture and groundwater.
- Download the program to compute the SPI with your data
- Learn about the SPI
- View archived SPI by climate division maps
The SPI tells you whether an area is dry or wet based on its historic record, and can be computed for different time intervals.