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Data & Maps

Historical Data and Conditions

By looking back at historical data, communities can get a better understanding of the drought and extreme weather threats to be prepared for. The resources below help document and quantify historical drought conditions in order to help inform planning. Three historical drought datasets can be explored side by side: the U.S. Drought Monitor (weekly, 2000–present); Standardized Precipitation Index (monthly, 1895–present); and June-July-August Palmer Modified Drought Index values from tree-ring reconstructions and instrumental data (yearly, 0–2017).


of the U.S. was in drought in September 2012, according to the U.S. Drought Monitor record since 2000


of the lower 48 states were in drought in Summer 1934, the most in the lower 48, according to the Living Blended Drought Product since year 0


of the U.S. was in Exceptional Drought (D4) in February 1977, according to the Standardized Precipitation Index (SPI) since 1895


of the U.S. was Abnormally Wet in May 2019, the most according to the Standardized Precipitation Index (SPI) since 1895

Explore Historical Drought Conditions

The U.S. Drought Monitor (2000–present) depicts the location and intensity of drought across the country. Every Thursday, authors from NOAA, USDA, and the National Drought Mitigation Center produce a new map based on their assessments of the best available data and input from local observers. The map uses five categories: Abnormally Dry (D0), showing areas that may be going into or are coming out of drought, and four levels of drought (D1–D4). Learn more.

Drought results from an imbalance between water supply and water demand. The Standardized Precipitation Index (SPI) measures water supply, specifically precipitation. SPI captures how observed precipitation (rain, hail, snow) deviates from the climatological average over a given time period—in this case, over the 9 months leading up to the selected date. Red hues indicate drier conditions, while blue hues indicate wetter conditions. Data are available monthly from 1895–present. Learn more.

* Currently, data are only available for the contiguous U.S.

In paleoclimatology, proxy climate data (e.g., tree rings, ocean sediments) can allow us to reconstruct past climate conditions before we had widespread instrumental records. The Living Blended Drought Atlas estimates average drought conditions each summer as far back as the year 0 by combining tree-ring reconstructions and instrumental records. Below is a reconstructed Palmer Modified Drought Index for each June–August. Red hues indicate drier conditions, while blue hues indicate wetter conditions.

* Currently, data are only available for the contiguous U.S.
D0 - Abnormally Dry
  • Short-term dryness slowing planting, growth of crops or pastures.
  • Some lingering water deficits
  • Pastures or crops not fully recovered
of U.S.
D1 - Moderate Drought
  • Some damage to crops, pastures
  • Streams, reservoirs, or wells low, some water shortages developing or imminent
  • Voluntary water-use restrictions requested
of U.S.
D2 - Severe Drought
  • Crop or pasture loss likely
  • Water shortages common
  • Water restrictions imposed
of U.S.
D3 - Extreme Drought
  • Major crop/pasture losses
  • Widespread water shortages or restrictions
of U.S.
D4 - Exceptional Drought
  • Exceptional and widespread crop/pasture losses
  • Shortages of water in reservoirs, streams, and wells creating water emergencies
of U.S.

Combine Historical Data

This tool allows you to combine multiple states or counties, so you can view historical conditions for a custom region.

Get Historical Drought Data

Drought Since 2000

The U.S. Drought Monitor (USDM) is a map released every Thursday, showing parts of the U.S. that are currently in drought. The USDM relies on drought experts to synthesize the best available data and work with local observers to interpret the information and is a joint effort of the National Drought Mitigation Center, USDA, and NOAA.

Drought Since 1895

Statewise time series graphs and downloadable data going back to 1895 from NOAA's National Centers for Environmental Information. Datasets include SPI (displayed above), Palmer indices, temperature, precipitation, and degree days.


Drought Since Year 0