two weeks early october

In early Oct. the only adversity you will encounter west of the Cascades, other than lousy traffic in the Seattle area, will be rain and likely lots of it. Bad snow in the mountains doesn't usually factor in until November.

One thing you might want to be aware of is the huge bridge at the mouth of the Columbia river connecting Astoria Oregon and Washington. If you take the coast route you will use it. There are other alternatives if you think it may be a little uncomfortable driving in your C. You can cross the Columbia river more inland if you look at maps and avoid the bridge or take I-5 for a while. Not that it is such a big deal, but I thought I would make you aware of it in case you get a little queasy about driving over bridges as huge as this sometimes in fog. Here is a link about the bridge.....

http://funbeach.com/local-attractions/astoria-megler-bridge/

Nothing will be closed due to snow. But a major fall storm might produce flooding and landslides anywhere in the region, including (or especially) along the coast. But you can't make long term plans around that sort of event.

The freeway route, I5, does not have passes in Washington. The only significant pass is on the Oregon/California border.

I agree with donn0128, Hwy 101 is a very nice alternative, much more scenery. Maybe drive down Hwy. 101 and go back via I-5. I have driven my camper from Oakland to Seattle in one day several times. Have a Great Trip!

Bob in Calif.

I5 will be no problem in October. As a nice alternative maybe try the coast on US101.