Well, even when we aren't in the midst of one of our sunniest summer streaks, you can tell them that no, it doesnt rain all the time here -- or even half the time -- or even 1/10th the time.
According to NOAA stats, if you add up all the hours it's rained and divide by the number of hours in the year, it really only rains in Seattle 9.4% of the time. Even in the soggy winter, it's at most 18% of the time.
And the wettest place around -- Forks and their 137 inches of rain a year -- it only rains 21% of the time (Although it's 33% in the winter.)
For More Information -- No. Hours Of Rain