Zeraati et al. (2026) Rapid soil moisture depletion during flash droughts accelerates wildfire spread in the United States

Identification

• Journal: Communications Earth & Environment
• Year: 2026
• Date: 2026-09-04
• Authors: Masoud Zeraati, Hayley Jane Fowler, Colin Manning, Christopher J. White
• DOI: 10.1038/s43247-026-04011-y

Research Groups

• School of Engineering, Newcastle University, Newcastle, UK.
• Tyndall Centre for Climate Change Research, Newcastle University, Newcastle upon Tyne, UK.
• Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, UK.

Short Summary

This study investigates the relationship between flash droughts (FDs) and wildfire spread dynamics across the conterminous United States. The results show that rapid soil-moisture depletion during FD events accelerates wildfire spread, with a 1.3-1.8-fold faster early burning rate compared to non-FD conditions.

Objective

• To quantify relationships between flash droughts and wildfire spread dynamics across land-cover types in the conterminous United States.
• To determine whether fires igniting after FD events spread more rapidly than fires not preceded by FDs, and compare these effects with fires occurring under conventional drought conditions.

Study Configuration

• Spatial Scale: Continental-scale analysis across the conterminous United States (CONUS).
• Temporal Scale: Analysis of wildfire clusters over a 24-year period from 2001 to 2024.

Methodology and Data

• Models used: Root-zone soil moisture (RZSM) definition for FD identification.
• Data sources: MODIS MCD12Q1 Collection 6.1 dataset, satellite observations of wildfire clusters.

Main Results

• Rapid pre-fire depletion of root-zone soil moisture provides a more direct pathway to accelerated wildfire spread than background dryness alone.
• Hazard ratios (HRs) exceeding one across all land-cover classes indicate consistently faster ignition of grid cells within fire clusters when fires occur following FD events.
• The proportional-hazards model assumes a time-invariant burn rate, though diagnostics indicate possible violations in four of the six analysed land-cover classes.

Contributions

• This study provides new insight into how flash drought can intensify wildfire impacts by linking rapid drying processes to wildfire spread dynamics.
• The results highlight the importance of considering both the rate and severity of drought in understanding wildfire behaviour.

Funding

• Not specified in the provided text.

Citation

@article{Zeraati2026Rapid,
  author = {Zeraati, Masoud and Fowler, Hayley Jane and Manning, Colin and White, Christopher J.},
  title = {Rapid soil moisture depletion during flash droughts accelerates wildfire spread in the United States},
  journal = {Communications Earth & Environment},
  year = {2026},
  doi = {10.1038/s43247-026-04011-y},
  url = {https://doi.org/10.1038/s43247-026-04011-y}
}