where is Washington State will you be touring? if you're here in Aug/Sept, chances are it'll be a lot dryer than touring anywhere in the east. pretty much the only chance of much rain would be if you're in the Olympic National Park area. it rarely rains in Washington that time of the year. plan on 70 and sunny west of the cascades, 80-90 and sunny east of that. even though the weather this year has been bizarre don't over prepare with a bunch of rain gear you wont need.