nClimDiv drought indices
Monthly drought indices for the 344 climate divisions of the contiguous United States since 1895: the Palmer Drought Severity Index, the Palmer Hydrological Drought Index, the Palmer Z index and the Standardized Precipitation Index at seven accumulation windows, computed from area-weighted gridded estimates of GHCN-Daily station data.
Rights
- Commercial reuse
- Yes
- Redistribution
- Yes
- Derivative use
- Yes
- Attribution required
- No
- Restrictions
- Applies to material authored by US federal agencies. Third-party material carried within a federal product may be separately protected.
- Terms last checked
- 27 August 2026
Access and coverage
- Publisher
- NOAA National Centers for Environmental Information
- Geographic coverage
- Contiguous United States, by climate division
- Temporal coverage
- 1895 onwards
- Resolution
- Climate division, monthly
- Update frequency
- monthly
- Formats
- txt
- Bulk download
- Available
- Registration required
- No
- Cost to Hydrionis
- Free
- Domains
- drought
Notes
Hydrionis holds four of the eleven published indices — PHDI, PDSI, SPI-1 and SPI-12 — as four separate metrics, because they disagree with one another by design and the disagreement is the information. There is deliberately no combined drought score: any weighting of these into one number is an editorial judgement wearing a measurement’s clothes. All are anomalies against NOAA’s 1931–1990 reference period, which is stated on every value because a standardised index without its baseline cannot be interpreted.
What Hydrionis holds from this publisher
The publisher’s own coverage is above. This is what Hydrionis has actually taken from it, at the subjects it measures — gauges, boreholes, reservoirs or places.
What is measured
- Palmer Drought Severity Index · index
- Palmer Hydrological Drought Index · index
- Standardised Precipitation Index (12-month) · index
- Standardized Precipitation Index, 1 month · index
How current it is
- Partial record held
- NOAA NCEI offers more than Hydrionis currently holds. The newest value here covers 2026-07; the gap is a deliberate limit on what has been collected, not a limit on the source. NOAA publishes eleven drought products at divisional, state, regional and national level. Hydrionis holds four of them at divisional level: PHDI, PDSI, SPI-1 and SPI-12. PMDI and the Palmer Z index are deliberately not held, and neither are the other five SPI windows.NOAA publishes eleven drought products at divisional, state, regional and national level. Hydrionis holds four of them at divisional level: PHDI, PDSI, SPI-1 and SPI-12. PMDI and the Palmer Z index are deliberately not held, and neither are the other five SPI windows.
Hydrionis products built from it
Where this publisher’s data reaches a reader. Each has its own page, with its licence and how to cite it.