Li et al. (2026) Wildfire synchronicity across European regions is favored by specific weather regimes

Identification

• Journal: Communications Earth & Environment
• Year: 2026
• Date: 2026-09-17
• Authors: Xinhang Li, Raul Roger Wood, Julia Miller, Dominik Büeler, Manuela I. Brunner
• DOI: 10.1038/s43247-026-03956-4

Research Groups

• Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
• WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland
• Climate Change, Extremes and Natural Hazards in Alpine Regions Research Center CERC, Davos Dorf, Switzerland
• Center for Climate Systems Modeling (C2SM), ETH Zurich, Zurich, Switzerland
• Federal Office of Meteorology and Climatology MeteoSwiss, Zurich-Airport, Zurich, Switzerland

Short Summary

This study analyzed synchronous wildfires across ten European regions from 2001 to 2020, attributing their seasonal occurrence and spatial extent to specific year-round weather regimes. It found that these regimes primarily modulate synchronous wildfires by driving warm and dry meteorological anomalies, suggesting an increased frequency of such events in a warming climate.

Objective

• To systematically analyze synchronous wildfires across ten European regions (2001-2020) and understand the meteorological conditions and large-scale weather regimes that favor their occurrence and spatial extent.

Study Configuration

• Spatial Scale: Ten European regions (Iberian Peninsula, western Mediterranean, eastern Mediterranean, France, the Alps, southeastern Europe, British Isles, central Europe, northeastern Europe, and Scandinavia), covering the European continent from -10.5°W to 32.0°E and 34.8°N to 71.2°N.
• Temporal Scale: Two decades (2001–2020) for wildfire observations and atmospheric reanalysis, focusing on seasonal and subseasonal timescales.

Methodology and Data

• Models used: Not applicable (no explicit climate or hydrological models were used for simulation; a weather regime classification scheme and the Canadian Fire Weather Index were applied).
• Data sources:
  • Satellite fire observations: FRYv2.0FireCCI51_6D global fire event dataset (derived from FireCCI51 250 m burned area and MODIS MCD14ML 1 km active fire products).
  • Atmospheric reanalysis: ERA5 global atmospheric reanalysis dataset for meteorological variables (2 m maximum air temperature, 10 m wind speed, 2 m relative humidity, total precipitation) and weather regime classification.
  • Land cover maps: European Space Agency Climate Change Initiative (for filtering fire events to near-natural vegetation).

Main Results

• Synchronous wildfires occur year-round across Europe, with seasonally varying frequencies; the strongest synchronicity is observed when considering all seasons (12 significant connections).
• Wildfire synchronicity is significantly enhanced by overlapping fire seasons between regions.
• Synchronous wildfire days consistently co-occur with warm and dry conditions, characterized by positive temperature anomalies and negative anomalies in precipitation and relative humidity across all European regions.
• Specific weather regimes modulate the occurrence and spatial extent of synchronous wildfires by driving these fire-conducive meteorological anomalies.
  • European Blocking (EuBL), Scandinavian Blocking (ScBL), and Zonal Regime (ZO) are the most important regimes favoring pairwise wildfire synchronicity.
  • EuBL promotes synchronicity between northern and western regions in spring, and shows a positive relationship with the spatial extent of synchronous wildfires in spring and fall.
  • Atlantic Ridge (AR) promotes north-south synchronicity in summer.
  • European Blocking is the most likely regime co-occurring with synchronous wildfires spanning large spatial domains (involving more than five regions) in spring and fall.
  • Greenland Blocking (GL) drives widespread cold and humid anomalies, impeding synchronous wildfire development.

Contributions

• Provides the first observation-based evidence of synchronous wildfire occurrences across Europe, addressing a critical knowledge gap.
• Establishes spatially and seasonally explicit links between wildfire synchronicity and predictable large-scale weather regimes.
• Identifies high-pressure conditions (associated with EuBL, ScBL, ZO) as a key circulation characteristic promoting continental-scale wildfire synchronicity, resolving the underlying meteorological drivers (warm and dry anomalies, and in some cases, wind anomalies).
• Offers actionable insights for improved operational early warning systems and enhanced preparedness for synchronous wildfire emergencies, facilitating more effective cross-border firefighting cooperation in Europe.

Funding

• ETH Zurich, Single-PI Grant “Synchronous forest fires in Europe under current and future climate conditions (SynFire)” (grant number 23-2 ETH-07).

Citation

@article{Li2026Wildfire,
  author = {Li, Xinhang and Wood, Raul Roger and Miller, Julia and Büeler, Dominik and Brunner, Manuela I.},
  title = {Wildfire synchronicity across European regions is favored by specific weather regimes},
  journal = {Communications Earth & Environment},
  year = {2026},
  doi = {10.1038/s43247-026-03956-4},
  url = {https://doi.org/10.1038/s43247-026-03956-4}
}