The monsoon has always been present Danny, as a matter of fact, the wilderness sees a majority of its non frozen precipitation between early July and early September, on average anywhere from 5-10" or more of rain falls. Far more then even the Sierras see during summer. For an example several stations in Big bear have already seen over 3 inches of rain since the new rain season began on July 1st, and Big Bear sees less then the wilderness as a good amount of the most intense storms form right between San Gorgonio and Onyx peaks and move into Big Bear where they eventually fade out as they move into the high deserts below. As for this week, there will be a good chance of some storms each afternoon, but not all of the wilderness will see rain, the northeast side of wilderness often sees a lot more monsoon activity then the southwest side.
For some details feel free to visit my site http://www.socalweather.net