Winter is when you will have a tailwind on the coast from the south, summer it's a Headwind..
The stream of hundreds of bike Tourists all ride southbound , for a reason..
Start in the Northern , Seattle, end, 101 west around the Olympic peninsula head south on the Coast.
cross bridge to Astoria , west end of town, take 202, Vernonia- Banks trail , to 26 then east to Portland.
south to north the inland route is probably a requirement.