"Snuffy \"Hub Cap\" McKinney"
writes:

Looks like we're in for rain every week or so in the PRC (Calif).
Grass is growing like crazy, with the weather still in the 60-70's.
What kind of treatment is good just before a 1-2 inch rain?

Simple answer:

NONE

Whatever you apply, it will get washed away.

--
Dan Espen