The significant wildland fire potential forecasts included in this outlook represent the cumulative forecasts of the ten Geographic Area Predictive Services units and the National Predictive Services unit.
A heat wave developed across the West Coast during the first week of September that resulted in hot, dry, and unstable conditions with explosive large fire growth. The Creek Fire in southern California produced multiple pyrocumulonimbus clouds including lightning and the first two pyrotornadoes ever surveyed by the National Weather Service (NWS). Fire activity also increased across much of the West in response to the heat wave and very dry fuels.
Multiple wind events resulted in significant large fire activity including a historic offshore wind event that began Labor Day and continued during the following few days. Rapid fire spread and extreme fire behavior developed on numerous new and existing large fires in Washington, Oregon, and California. Other notable wind events led to significant increases of fire activity in Montana and California early and late in September, respectively.
Air quality and smoke concerns were greatly exacerbated on the West Coast and eventually most of the West for much of September. However, a series of upper-level troughs produced wetting rain across portions of the Pacific Northwest and Northern Rockies later in the month. This helped reduced fire activity and significant fire potential late in the month across these regions. A pause in fire activity was observed in the Rocky Mountain Area due to cold, wet conditions during the week of Labor Day, but rebounded later in the month.
La Niña and current fuel conditions are the main drivers of significant fire potential through fall and into winter. Drought conditions are expected to continue for much of California, the Great Basin, and the Southwest through October with drying expected to increase across portions of the southern Plains and Southeast. Significant fire potential remains above normal for California due to the number of active large fires, near record dry fuels, and offshore wind events.
Above normal significant fire potential is expected across much of California, Arizona, eastern Nevada, Utah, Colorado Rockies, and southern Wyoming in October. However, fire activity and potential will likely diminish across the West, except for portions of California, and remain normal over the Eastern and Southern Areas through November. Elevated periods of fire activity are likely in portions of Oklahoma and Texas and possibly in other locations in the Southern Area during fall into winter.