alt Hacker NewsI had wondered about this. What you're saying makes sense, but, living in Portland, I had come up with my own explanation. When I see 10% here, I usually take it to mean something like "it will rain for six minutes every hour", or for 10% of the day.
That's interesting. If you're usually rained on when there's a 10% chance of rain, that suggests that either you live in a particularly rain section of Portland, or that you move around to a large percentage of the Portland area each day, or that somebody's using a different definition for "chance of rain" than I do. I wonder which one is going on.