Five of California’s ten largest wildfires occurred in 2020, with the largest complex shattering the previous record by more than 100 %. The year follows a decade containing extraordinary fire activity. Trend investigations focused on changes in human activities and atmospheric thermodynamics, while the impacts of changing atmospheric dynamics are largely unknown. Here we identify extreme weather types (XWTs) associated with historically large daily burned areas in eight Californian regions. These XWTs characterize dominant fire weather regimes varying in fire behavior types (plume-driven vs. wind-driven fires) and seasonality. 2020’s exceptional fires partly occurred during previously unrecognized XWTs, whose characteristics and recurrence intervals were largely unknown. Most of the strongly large-scale forced XWTs such as Santa Ana and Diablo events increased in frequency during the 20th century particularly in the Sand Diego and Bay Area region. These changes are likely not anthropogenically caused and predominantly due to climate internal variability. However, raising greenhouse gas concentrations significantly decrease thermal low XWTs in southern and increase them in central California. These XWTs occur during the hottest time in the year and will alter fire risk in the summer season.