This is a perfect time of year to plant trees as they need water to get established and that will be plentiful in the next few weeks. I have many to transplant as well.

Provided your soil is not overly saturated, you can still plant. Planting now is still advantageous over spring planting and as long as the weather cooperates, will remain so throughout much of winter. Roots of woody plants are still quite active until soil temps drop below 40F, which is not a common occurrence in many parts of the NW unless we are hit with an extended cold spell.

Soils that are too wet will be a problem - you can easily impact soil structure by working saturated soils, so allow sufficient time to dry out, if possible. And pay attention to your drainage - if working in heavy or clay soils where drainage may be an issue, a shallow, wide planting hole is preferable to a deep one. Plant high and apply a mulch to even the high rootball. And avoid amending the planting hole - backfill with the indigenous soil.

If intended planting sites now soggy dump topsoil on and plant in that, above the wet area. If intended planting site actually flooded, puddling several inches deep or about to be it may be time to reconsider planting there, as if it gets too wet once there it will do it again later.

Here is a link that might be useful: Planting Fact Sheet

Thanks everybody. I guess my question is what is oversaturated? I have never planted in the rain before. I just heard on the news that Portland got as much rain in 5 days as we normally get in a month. And it's still raining!

I stuck a shovel in the soil and while it's really wet there aren't standing pools of water. I can easily squish the soil into a little ball of sticky clay though. I have not amended the soil anywhere except one area where I'm putting in azaleas.

Planting in topsoil doesn't sound pratical for my situation as the trees are on the large side & I wasn't planning on an elevation change.

The soil should crumble after you make a ball in your hands.
If the ball stays sticky and intact, it may be too wet, and working it will ruin the soil structure.

It sounds like your soil has adequate drainage but not really sharp drainage. With all the rain we just had, I would say wait until we get a few dry days then go for it.

Yes, I think you're right Ian. I just found this on the internet:

www.hort.purdue.edu/ext/wetsoil.html