The diner that Ponch and John are drinking coffee at during the rainstorm is now (as of 2021) 'Tuts' Mediterranean Grill, 12114 Washington Blvd in Culver City and it looks surprisingly the same.
This is the first episode in the series where Jon and Ponch are seen wearing their long sleeve uniforms.
They show Jon and Ponch out during rain. In general, when it is raining, CHP motor officers park their bikes and take a car because it is safer.