Current and Historical Drought

For Public Health

At a glance

Data on drought duration, severity, and projections can be used to better understand the connection between drought, other environmental conditions, and health effects. Many factors influence how drought will affect a community. However, drought trend data and other related indicators can be used to prepare for and prevent potential health risks.
Cracked, brown earth from a dry river bed.

We Track That

The Tracking Network includes data on drought duration, severity, and projections. Sources include the United States Drought Monitor (USDM), including the maximum drought severity (MAXUSDM), the Standardized Precipitation Evapotranspiration Index (SPEI), and the Monthly U.S. Drought Outlook (USDO). These datasets track drought trends and monthly projections in the United States.

Types of Data

Current and Historical Drought

The Tracking Network provides current and historical drought data from both the SPEI and the USDM. The SPEI and USDM drought measures are calculated using different methodologies. But both can be used to monitor trends over time. SPEI data are available from 1980 through the present. USDM data are available from 2000 through the present.

Specific measures include the following.

Counties Currently Experiencing Drought: Data are reported weekly. It reflects whether 50% or more of a county was in moderate drought or greater for the latest week.

Maximum Number of Consecutive Weeks: These data show how many consecutive weeks a county was in drought, by year.A

Total Number of Weeks (Cumulative): These data show the number of weeks a county was in drought. These values are cumulative and cover the entire period of record.A

Total Number of Weeks (Yearly): These data show the total number of weeks a county was in drought, by year.A

Monthly Maximum Drought Intensity (MAXUSDM): This data is a metric derived from USDM but represents the maximum drought intensity, referred to as MAXUSDM.

Projected Drought

The Tracking Network provides projected drought data from the USDO. The drought outlook provides a monthly projection for drought conditions in the U.S.

Monthly Drought Outlook (USDOCAT): This data is derived from the Monthly U.S. Drought Outlook and predicts the next month's drought conditions.

Access the Data

Use the Data Explorer to create custom maps, tables, and charts.

View data in simple Quick Reports.

Get machine-readable data from the Application Program Interface (API).

Data in Action

Use the Tracking Network's drought measures to examine local, state, regional, and national trends in drought at the county level. Looking at trends can help us learn more about the relationship between drought-related environmental exposures and health outcomes.

Public health professionals, water and sanitation officials, policy makers, and others can use the data for the following purposes.

  • Allocating drought relief
  • Supporting community planning efforts
  • Informing other drought discussions

Learn More

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Content Source:
National Center for Environmental Health
  1. These data can be stratified by categorial drought severity or cumulative drought severity.