On its way to becoming one of the largest fires in California history, the North Complex (composed of multiple fires, most of which were suppressed, but the Claremont/Bear fires merged) grew by over 210,000 acres on 9/8-9/9, driven by strong northeasterly winds. CAWFE simulations show these were concentrated in the river valley of the Middle Fork of the Feather River, with strong pulsing gusts present over the lower foothills above and near Oroville.