The California Highway Patrol has released its tallies of fatal collisions per month. The statistics also show car accident data about crashes that did not result in death but injuries. It is interesting to note that this compilation of data represents a ten-year summary of cases. July. In 2004 and 2005, the month of July was the deadliest for California drivers. August. In 2006 and 2007, the figure shifted to the month of August. September. In 2008, the month of September was the deadliest for motorists. October. In 2009, 2011.