PDSI: University of Idaho Palmer Drought Severity Index

Dataset Availability
1979-03-01T00:00:00 - Present
Dataset Provider
Earth Engine Snippet
pdsi drought conus crop palmer geophysical climate idaho uofi


The Palmer Drought Severity Index dataset provides high spatial resolution (~4-km) thrice-monthly estimates of this widely used measure of integrated water supply and demand anomalies across the contiguous United States from 1979-present. The PDSI is calculated using precipitation and potential evapotranspiration derived from the gridded meteorological dataset of Abatzoglou (2013).

Potential evapotranspiration is computed using the Penman-Montieth equation for a reference grass surface. Available soil water holding capacity in the top 2.5m of the soil was derived from the STATSGO soils database and used in the computations. Whereas PDSI has typically been computed on monthly timescales, we compute these data three-times a month to provide more timely updates. Due to the spin-up of PDSI calculations, data for the first year of record should be used sparingly.

This dataset contains provisional products that are replaced with updated versions when the complete source data become available. Products can be distinguished by the value of the 'status' property. At first, assets are ingested with status='early'. After several days, they are replaced by assets with status='provisional'. After about 2 months, they are replaced by the final assets with status='permanent'.


2.5 arc minutes


Name Min Max Description
pdsi -11.94* 17.92*

Possible values: 4.0 or more (extremely wet), 3.0 to 3.99 (very wet), 2.0 to 2.99 (moderately wet), 1.0 to 1.99 (slightly wet), 0.5 to 0.99 (incipient wet spell), 0.49 to -0.49 (near normal), -0.5 to -0.99 (incipient dry spell), -1.0 to -1.99 (mild drought), -2.0 to -2.99 (moderate drought), -3.0 to -3.99 (severe drought), or -4.0 or less (extreme drought).

* estimated min or max value

Image Properties

Image Properties

Name Type Description
status STRING

'early', 'provisional', or 'permanent'

Terms of Use

Terms of Use

This work (METDATA, by John Abatzoglou) is in the public domain and is free of known copyright restrictions. Users should properly cite the source used in the creation of any reports and publications resulting from the use of this dataset and note the date when the data was acquired.


  • Abatzoglou J.T., R. Barbero, J.W. Wolf, Z. Holden (2014), Tracking interannual streamflow variability with drought indices in the Pacific Northwest, US, Journal of Hydrometeorology, 15, 1900-1912.

Explore in Earth Engine

var dataset = ee.ImageCollection('IDAHO_EPSCOR/PDSI')
                  .filter(ee.Filter.date('2018-07-01', '2018-08-01'));
var pdsi = dataset.select('pdsi');
var pdsiVis = {
  min: -5.0,
  max: 10.0,
  palette: ['red', 'yellow', 'green', 'cyan', 'blue'],
Map.setCenter(-115.356, 38.686, 5);
Map.addLayer(pdsi, pdsiVis, 'PDSI');