climate_indices

Open-source Python library by James Adams that computes drought, fire and flood-potential indices such as SPI, SPEI, the Palmer family and KBDI from station or gridded precipitation and temperature.

What is reusable: open sourceunknown dataAPI unknownunknown participation BSD-3-Clause

The code began at NOAA's NCEI and NIDIS as reference implementations of climate indices.¹ Version 3.0.0 covers potential evapotranspiration and three hazard families:^3,5

Drought and moisture balance: SPI, SPEI, PNP, PCI, EDDI, and the Palmer indices PDSI, PHDI, PMDI, Z-Index and scPDSI.^1,5
Potential evapotranspiration, the water that would evaporate and transpire if it were available: by Thornthwaite, Hargreaves or FAO-56 Penman-Monteith.^1,5
Wildfire: KBDI, the Canadian FWI system, Fosberg, Hot-Dry-Windy and Haines.³
Flood potential: effective precipitation, EDI, the Flood Index and the Antecedent Precipitation Index.³

An energy family is listed as still in development.⁵

Inputs are precipitation and temperature series, from stations or from NetCDF grids (a common file format for gridded climate data).^1,4 The flood indices measure potential, not observed, flooding, and their external validation is still a gap.³

It installs from PyPI and runs on Python 3.10 to 3.14.^1,2 An optional Rust backend speeds up eligible calculations without changing the Python API, and gridded runs are vectorised over time-major blocks.³ The NumPy API is stable; the xarray API is marked beta.^1,3 The licence is BSD-3-Clause.¹

Version 3.0.0 was released on PyPI on 12 October 2026.^1,2 The Read the Docs site still documents version 2.0.1.⁴