Day of burning dataset: Biogeography of daily wildfire progression

<p><strong>Introduction</strong></p> <p>Climate change is predicted to increase the frequency of extreme single-day fire spread events, with major ecological and social implications. In contrast with well-documented spatio-temporal patterns of wildfire ignitions and perimeters, daily progression remains poorly understood across continental spatial scales, particularly for extreme single-day events ("blow ups"). Here, we characterize daily wildfire spread across North America, including occurrence of extreme single-day events, duration and seasonality of fire and extremes, and ecoregional climatic niches of fire in terms of Actual Evapotranspiration (AET) and Climatic Water Deficit (CWD) annual climate normals.</p> <p><strong>Methods</strong></p> <p>Remotely sensed daily progression of 9,636 wildfires ≥400 ha was used to characterize ecoregional patterns of fire growth, extreme single-day events, duration, and seasonality. To explore occurrence, extent, and impacts of single-day extremes among ecoregions, we considered complementary ecoregional and continental extreme thresholds (Ecoregional or Continental Mean Daily Area Burned + 2SD). Ecoregional spread rates were regressed against AET and CWD to explore climatic influence on spread.</p> <p><strong>Results</strong></p> <p>We found three-fold differences in mean daily area burned among 10 North American ecoregions, ranging from 260 ha day^-1 in the Marine West Coast Forests to 751 ha day^-1in Mediterranean California. Ecoregional single-day extreme thresholds ranged from 3829 ha day^-1 to 16626 ha day^-1, relative to a continental threshold of 7173 ha day^-1. The ~3% of single-day events classified as extreme cumulatively account for 16-55% of ecoregional total area burned. There were four-fold differences in mean fire duration, ranging from 2.7 days in the Great Plains to 10.5 days in the Northwestern Forested Mountains. CWD had a weak positive relationship with ecoregional spread, and there was no pattern for AET.</p> <p><strong>Discussion</strong></p> <p>Regions with shorter fire durations had greater daily area burned, suggesting a paradigm of fast-growing short-duration fires in some regions and slow-growing long-duration fires elsewhere. Although climatic conditions can set the stage for ignition and influence vegetation and fuels, finer-scale mechanisms likely drive variation in daily spread. Daily fire progression offers valuable insights into the regional and seasonal distributions of extreme single-day spread events, and how these events shape net fire effects.</p>