I grew up on the Oregon coast, so I can vouch for the truth of this one. I found while living there that if you interpret the "X% chance of rain" in the weather forecast as "it will rain X% of the day", the weather forecasts get a lot more accurate. ;)
Having been raised in Utah, I didn't understand the nuances of the weather forecasts when I moved here. Like the difference between "partly sunny" and "partly cloudy." And there's a difference between "rain" and "showers." Like you say, you can pretty much just count on rain!