24 hour accumulation of precipitation to 7am on the 19th in Davis was about 1″. Below is the record (for Sacramento, at least) daily rainfall values for the month of September. A 1″ storm would easily be a top 10 daily accumulation. So, this rain was in rare company but was hardly unprecedented.
Records for the 23rd, 24th, and 25th were all set in 1904. Assuming that was just one storm, total rainfall from that single event was (at least) 3.50″!