Interesting article on CNN about the possibility of another California megaflood -- one which happens occasionally, but hasn't been seen in 160 years: https://www.cnn.com/2022/08/12/weath...udy/index.html
In 1861 and 1862, there was a pattern of torrential rains which pounded California, burying Sacramento under 10 feet (!!) of water:
That's an actual photo of 1861 Sacramento.
It is believed that this will happen again sometime in the next few decades, and in fact could happen at any time.
I have seen some flooding in California, but never anything like described in this article.