Quote Originally Posted by Editor
Rain is likely for most, if not all, of the journey. Although snow is possible when you cross the Cascade Mtns. What route were you planning on using?
If you're going up I-5, you might see a little snow and ice going over the Siskiyou Pass (this is located shortly after crossing over the border from California to Oregon). And there's a good chance that you will see some of this in eastern WA. However, when you are on the major highways, it normally doesn't stick or last too long. They are pretty good about keeping these clear and the heat of all the cars on the road tend to help things melt fairly quickly.

And you can avoid any snow/ice problems in the Cascades by avoiding going over the Cascades. Just turn east in Portland and go to Spokane along the Columbia Gorge on I-84. You'll then take I-82 north to Kennewick, then 395 to meet up with I-90 that will take you the rest of the way into Spokane.

What route were you planning on taking? 2-3 days should be enough in most road/weather conditions. Although it wouldn't hurt to plan an extra day in order to have time to do a bit more sightseeing and to allow a buffer in case you don't get poor weather and roads for a short part of your trip.

It would be a very odd occurrence if you have any problems along the majority of your route. Any closures or slow-downs due to weather would likely be very termporary and very local.