Future fire weather projections show the importance of mitigation and adaptation for dynamic fire management

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Abstract. Understanding future shifts in fire weather (FW) risk across peak-season, transitional, and off-season periods is crucial for adapting fire preparation and management to climate change. Fire management planning depends not only on reducing fire risk through climate change mitigation, but also on how residual risk evolves under different warming pathways, including low levels of global warming. Additionally, while most FW projections focus on peak-season severity and length, fire management decisions – including prevention, preparedness, and controlled burning- are made throughout the annual cycle. This creates a growing information gap between climate-driven shifts in fire risk under different mitigation scenarios and year-round fire management frameworks. To address this, we explore future climate-driven FW projections using the McArthur Forest Fire Danger Index (FFDI) and a large perturbed-physics ensemble, enabling a systematic assessment of uncertainty and confidence in projected changes globally and across three focus regions: Australia, Brazil, and the United States of America. We evaluate future FW across all phases of the annual cycle relative to both a historical baseline (1986–2005) and a recent reference period (2004–2023), under three Global Warming Levels (1.5, 2.0, and 4.0 °C) and two emissions scenarios (RCP2.6 and RCP8.5). In addition to changes in season length and peak FFDI, we quantify transitions between meteorological FW periods and shifts in low FW windows, linking projected climate change impacts directly to the timing and feasibility of Integrated Fire Management (IFM) activities. We project a global rise in FW at all GWLs, with the largest increases in Australia, then Brazil and the USA. At 1.5 °C, 31 % (25 %–36 %) of global burnable land area is projected to see more days with Very High fire weather (FFDI ≥ 24) than in the baseline period of 1986–2005. Higher GWLs drive further increases, with more than a threefold rise in days with Very High FW from 2.0 to 4.0 °C. The transition from preparation periods to fire season advances by 7–36 d (Australia), 12–32 d (Brazil), and 5–36 d (the United States of America) at 2.0 °C. Low FW windows persist, offering crucial opportunities for out-of-season preparation, though they narrow with warming. Our findings highlight the dual need for mitigation and adaptation strategies, including accounting for changes in out-of-season fire risks. We offer an initial step toward a more dynamic form of IFM by illustrating how climate projections, impact metrics and seasonal diagnostics can be combined to inform preparedness, flexible planning, and providing a foundation for operational dynamic IFM.

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