When Do The Grunion Run. A grunion run refers to the activity of catching grunion when they come out at night to spawn during the spring and summer in southern california. They can start as early as 9:00 pm or as late as midnight or even 1:00 am.
The phenomenon of grunion runs is a truly unique and fascinating sight to behold. We can see that the night time high tide doesn’t surpass the height of the day time high tide until the third night (march 9th) of this next predicted grunion run.