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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).

54.8%

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

66.2%

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

22.9%

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

82.3%

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

U.S. Drought Monitor (2000 - Present)

U.S. Drought Monitor Category
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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.

Time Period (Years): to

Data and Map Gallery
Representative image of the U.S. Drought Monitor

U.S. Drought Monitor (USDM)

NOAA and its partners publish regional reports each quarter, summarizing weather, impacts and predictions.

Period of Record
2000 - present
File Format
images
text (ascii)
csv
shapefile
kml
An example Palmer Modified Drought Index reconstruction map for 1782 CE.

Living Blended Drought Atlas (LBDA) - Historical Drought Information

The Living Blended Drought Atlas (LBDA) is a recalibrated data series of June-July-August Palmer Modified Drought Index (PMDI) values by United States climate division, compiled by blending tree-ri

Period of Record
Historical data
File Format
images
text (ascii)
netcdf-4
Preview of NCEI landing page for paleoclimatology datasets

Paleoclimatology Data

NCEI provides the paleoclimatology data and information scientists need to understand natural climate variability and future climate change.

Period of Record
Historical data
Example map of Europe showing June-August PDSI in 1540

Old World Drought Atlas

The OWDA provides new data to determine the causes of Old World drought and wetness and attribute past climate variability to forced and/or internal variability.

File Format
images
text (ascii)
netcdf-4
Global Historical Climatology Network mapping system showing PMDI

Global Historical Climatology Network (GHCN)

Global Historical Climatology Network (GHCN): an integrated database of daily climate summaries from land surface stations across the globe, including a common suite of quality assurance reviews.&n

Period of Record
1832 - Present (not all data available for all periods)
File Format
pdf
text (ascii)
csv
Historical Water Watcher example image

Historical Water Watcher

This tool, available as part of The Climate Toolbox, provides maps and summary tables of different drought types, such as agricultural and meteorological drought, for a location in the contiguous U

Period of Record
Current Conditions, Historical data (period of record varies)
File Format
images
pdf