CAL FIRE provides information about current fires as well as historical data. The picture here is from their incidents page where users can choose current fires or select particular year. For active incidents the right side bar provides the status of current fires. The stats and events page has historical information such as the top 20 fires. There is also a page with historical acres burned by year, although currently updated to only 2018 which was a record year of just under 2,000,000 acres burned.
The climate.gov article Over a million acres burned in California in second half of August 2020 by Tom Di Liberto (8/26/2020) provides some context about CA wildfires and connection to climate change.
