Deforestation and draining of the peatlands in equatorial SE Asia has greatly increased their flammability, and in September–October 2015 a strong El Niño-related drought led to further drying and to widespread burning across parts of Indonesia, primarily on Kalimantan and Sumatra. These fires resulted in some of the worst sustained outdoor air pollution ever recorded, with atmospheric particulate matter (PM) concentrations exceeding those considered “extremely hazardous to health” by up to an order of magnitude.

Researchers present a percentile-based calibration of the Canadian Forest Fire Weather Index (FWI) System for the United Kingdom (UK), developed from numerical weather prediction data, and evaluate it using historic wildfire records. The Fine Fuel Moisture Code, Initial Spread Index and final FWI component of the FWI system show the greatest predictive skill for UK wildfires. The findings provide useful insights for any future redevelopment of the current operational UK fire danger rating system.