i have never waited due to the rain. if the run-off is that bad, i just keep my head above the water, and try to always keep water from getting up my nose. if I get out and have a head full of water...i netti-pot it out.
Some of the best surf has been right after a heavy storm.
I'm thinking that it would take some time for all the run-off to mix into the ocean, the worst of it might be the next day or hours later.
I went in after work yesterday, water was dirt... just didn't fall...
you could get Hepatitis, some sort of stomach parasitic bug that keeps you on the bowl for a day or so, a very painful ear infection that lasts a few days, or absolutely nothing. I wouldn't stay out of the water if it was good. Drink a lot of water, do the neti pot thing, take your vitamins.