How wet is Seattle?
Both cities are quite hilly, but it's the surrounding mountains that really cause the difference in precipitation. To confuse things even more, just 10 miles east, west, south, or north of downtown Seattle annual precipitation totals can easily be 10 to 20 inches more.
Precipitation totals for: Atlanta 50, Boston 43, Buffalo 41, Cleveland 38,Houston 54, Minneapolis 29, Nashville 48, New York City 48, Philadelphia 42, Portland 37, Salt Lake City 16, San Francisco 22, St Louis 38 and Washington DC 39
Normally,wind patterns in the Seattle area come in from the west off the Pacific Ocean. Before they reach the city, however, the Olympic mountains, just 50 miles west of Seattle, intercept most of this moist airflow. Rainfall in the Olympics approaches 200 inches a year, resulting in a temperate zone rainforest. Hilly areas surrounding Seattle intercept additional moisture so that by the time Pacific air masses reach reach Seattle most of the moisture has been removed.