Tomorrow is May 1.
My grandmother always said that if you get wet in the first rain of May,
you'll be healthy all year.
I do what my grandmother said.
Rain's predicted for tomorrow around here.
If you're out west, you may have to wait.
If it doesn't rain where you are in May, I don't know what to tell you.
I interpret 'wet' rather liberally.
(But then I would, wouldn't I?)
One raindrop will suffice -- but actually standing in the rain for a bit is more fun.