We will be visiting the Troutdale area September 28 and 29. Will there be fall foliage colors at that time of year? Thanks
The definitive answer is maybe.
You might take the Historic Columbia River Highway towards Multnomah Falls or I-84 as the altitude will make color change quicker.
Here is some reading, hope it is helpful. The geography of this area supports Mrs. O's "maybe".
I'm from New England, and it is far more predictable (and, frankly, far more beautiful) there.