Hi Lars,
You've a wonderful trip ahead, and are very wise to plan for it starting now. We see a *lot* of cycle-tourists on the Oregon Coast, with a large number of non-Americans coming from Germany. It looks like an Ortlieb and Tubus factory rally each summer! I saw my first-ever pair of Ortlieb panniers on a German tourist's bike there many years ago.
For the Oregon stretch, you're definitely wise to go North-to-South, as the prevailing winds will be with you, you'll be on the ocean side for the best views of the seacoast and magnificent hidden beaches, and -- most importantly -- the traffic-side bike lanes are really configured for going that direction. Going South-to-North is a nightmare for cyclists and drivers alike, with narrow-to-nonexistent lanes, blind corners, and terrible headwinds. Doesn't seem to stop people, though.
Again, as far as the Oregon leg is concerned, I think your timing will be perfect. Summers on the coast here can often be damp, cold, and foggy, with August, September, and especially October being among the most sun-filled. Coast weather is an inverse mirror of what we have in the Valley -- hot/sunny here, cold/wet there and vise versa. The weather will improve as you go further South, and you're in for such a treat. Highlights will likely include the Bodega Bay area north of San Francisco, and then on down to San Diego...sublime.
Your timing will put you in peak whale-migration season, and there's a very good chance you'll spot a number right offshore. I was over at Yachats last week and saw more than a dozen, spouting and frolicking about 300m -- and closer! -- offshore. If you have room, be sure to tuck in some small binoculars or a long camera lens.
As for traffic, you'll have a *lot* of tourist traffic as Americans try to squeeze in a last bit of vacation before Labor Day (September 3rd this year). After Labor Day, it is like someone threw a switch or turned off the tap and car traffic is greatly reduced.
If you could start after Labor Day, you'll have a much quieter time in terms of car traffic. Lodging of all sorts will be more available, and you'll avoid the "tourist burnout" that can sometimes affect the locals. The downside is some services and such that are wholly tourist-dependent may be avaiLable at reduced levels.
Oregon has a number of miimalist "hiker-biker" camps available along your route, and I believe the same holds true for Washington and California. Cyclists don't need the formal amenities RV (caravan) users do -- no electrical or sewer connections, and small spots are fine. The parks department recognizes this, and makes more "traditional/minimal" facilities available, and these often remain unfilled even if the rest of the parks are full-up with no vacancy signs. Don't forget (if you're wild-camping) the side roads on the land-side of Highway 101. These often go up into the hills and just a wee bit off the main highway you can find some really nice spots to stay the night unobtrusively. Do watch for sap dripping from the wind-sculpted shore pines...it is awfully sticky and hard to remove if it gets on your tent or gear and often coats the brush and ground beneath. This caution holds true in formal camps as well.
I would caution you to take a lock of some sort, even though the bulk of tourists to the Pacific Coast don't, judging by the many bikes I've seen left unlocked outside cafes and grocery stores. This will be a greater necessity in the busier, more populated areas of California, but it is a caution well-heeded Up North as well. I've seen tourists after they returned to find their loaded bikes...gone!...and I don't think there could be an emptier more-lost feeling. Who needs that on a trip? Better to toss in at least a small cable lock to prevent a quick wheel-away of the parked and loaded bike. Always take your handlebar bag, with your documents, money and cards when you leave the bike; they're most frequently targeted by thieves who have learned that's where the Good Stuff lives.For the most part, theft is much less a problem on the Oregon Coast than it is here in the Willamette Valley, but why take the chance?
Take a variety of clothing, as well...stuff you can layer. Though the temperatures aren't extreme, it can still feel cold in the morning due to fog and damp; the afternoons will often be sunny and reasonably warm except for the wind, which you'll be traveling with (tailwinds!). As you go South and progress toward Southern California, you'll have consistently warm, nice weather that time of year, so summer-oriented clothing would be a good choice there; a real contrast compared to raingear and a light fleece Up North. The winter storms come from the South, but you won't find any at the time your trip is scheduled. You won't want to, either; one of last winter's storm winds topped 119mph/192kph.
You'll likely make pretty good time given the prevailing tailwinds, but this will be offset to a degree by the hills you'll encounter. At least here in Oregon, you're unlikely to find the hills terribly steep. For reference, my father (when he was in his mid-70s) and I managed 92mi/148km one day from Yachats to Reedsport and then inland on the Smith River Road. He did fine. Most people who do the trip you're planning stay pretty close to the ocean and ride pretty much just on Highway 101. There's not so much to see right off 101 in Washington and Oregon, but in California, I think you'll want to budget a bit of time to see some of the places nearby. If you can find secure lodging, the Marin Peninsula (Palo Alto, Mill City, Atherton...and Stanford University) is gorgeous to see by bus or bike, and San Francisco can be a nice waypoint if your itinerary takes you near the City itself. I love Carmel, CA (actor Clint Eastwood was their mayor for a time) and would have to see Mazda-Laguna Seca Raceway, but part of me still loves motor racing. You've got a long ways to go, and a reasonable time to do it. I think you'll do fine, see a lot, and have a wonderful time.
Best of luck!
Dan.
