97 from Toppenish, WA to Klamath Falls

Inland Washington and Oregon get cold is a cold air mass drops south from Canada. In effect if it's cold there, it's because you brought it with you. :)

If there's a high pressure inland, and low pressure on the coast, then the cold can flow through and over the mountains creating cold and, sometimes, snow along I5. Basically it's the same sort of conditions that produce cold and snow around Vancouver.

In the near future, Washington is getting hit with a lot of wet weather. I imagine it's the same further south, though I haven't checked. US97 usually is drier than I5. In southern Washington and northern Oregon US97 crosses dry country. Some canyons are even sage brush and pinion pine, as in Utah. Further south in Oregon it is Ponderosa Pine territory. SE Oregon is an extension of the Nevada basin and range desert, complete with salt flats.

Thanks all for your responses. Weather will determine our route this time, as we are heading out Sunday for our trip south and we will try go where the snow don't blow, well hopefully. Actually we have done a number of trips in mid January south from the Alberta border on I 15 through Montana, Idaho and Utah, and have had good drives and not so good drives. Suffice to say we have never had to delay our trip south due to weather, but watch the weather religiously and change our dates accordingly.

This trip south however, is through new territory at this time of year and are aware of being closer to the coast and storms that could blow through. We have looked in detail on the highway 97 drive and prefer that route, but have I 5 as an option. The interstates allow more rest stops and tank fills, and the older we get, the more often we need to "empty".

There is no rush to get out of the pending cold, but getting out of the cold is a pending rush!
Safe travels all!!

I just spent a week in Bend and the wx was pretty decent. Did see some rain, which fell as snow high in the mountains, but nothing as low as the 3500' passes. It would be pretty rare for a heavy snowfall that "early" in the season along 97. December through February, look out. +1 on tripcheck

It is a major highway so no worries there. Snow? Sure at 4000 foot elevations you can see snow any month of the year.
Two resources to look at. Weather bud and tripcheck. Tripcheck will show you live traffic cams for the entire state.

It is unlikely, but not impossible, that there will be much snow on Hwy 97 in early November. There could be some light dustings that would quickly melt off and you are likely to have frost in the mornings though.
That time of year it is always a good idea to check with Trip Check prior to traveling to verify conditions.

Safe travels,
Steve

Hwy 97 from Bend south through Klamath Falls is on the back side of the Cascades and in higher elevations. When it does snow in this area, it can be a bit nasty. If no storms coming through, it should be okay. At least with weather forecasting technologies now a days, you can keep track of the storms and also check the traffic cams located along the way to see how they look.