Let's face it, Seattle's weather has a bad reputation. As they say out here, "The rain in Spain stays mainly in Seattle." I wish I could tell you that it isn't so, but I can't. It rains in Seattle -- and rains and rains and rains. However, when December 31 rolls around each year, a funny thing happens: They total up the year's precipitation, and Seattle almost always comes out behind such cities as Washington, Boston, New York, and Atlanta. So it isn't the amount of rain here that's the problem -- it's the number of rainy or cloudy days, which far outnumber those of any of those rainy East Coast cities.
Most of Seattle's rain falls between October and April, so if you visit in the summer, you might not see a drop the entire time. But just in case, you should bring a rain jacket or at least an umbrella. Also, no matter what time of year you plan to visit Seattle, be sure to pack at least a sweater or light jacket. Summer nights can be quite cool, and daytime temperatures rarely climb above the low 80s (upper 20s Celsius). Winters are not as cold as they are in the East, but snow does fall in Seattle.
Because of the pronounced seasonality of the weather here, people spend as much time outdoors during the summer as they can, and, accordingly, summer is when the city stages all its big festivals. Because it stays light until 10pm in the middle of summer, it's difficult to get Seattleites indoors to theater or music performances. But when the weather turns wet, Seattleites head for the theaters and performance halls in droves.
