We went out to visit friends in Central Oregon (near Redmond..) every year for about a decade from the mid 90’s on. Usually we went in September, but made the trip in August a couple times.
August can be tough out there, at least in the places that I’m familiar with. The east side of the Cascades is high desert and it gets hot, really hot. I always did OK fish wise, though. You just have to pick your times and places.
If you have to go out in August, here are some potential destinations all within 2-3 hours of Bend/Redmond.
1) I’d forget about the main Deschutes, even though the headwaters (above Crane Prairie) and the top of the really big water (below Pelton Dam and down through Mecca Flats, etc.) will have decent water temps. Except for an hour or two in the evening or morning, you’ll broil your brain.
2) The Metolius is a good choice. Mostly wooded and even in the hottest part of August, I’ve never taken a water temp over 55F. I’d stay on the upper 10 miles or so of it, above what the locals call the “Gorge”. It isn’t that big, but it can be a mean river to wade with lots of very deep slots, etc. The upper Metolius, especially from around Camp Sherman up is a lot more friendly and there are plenty of fish. This is also the busiest section of the river, though. The fish are not easy. It is about the most technically difficult river I’ve ever fished and can be stingy. It also may be the most beautiful river of its size I’ve ever been on.
3) The Fall River that runs into the Deschutes not too far out of Sunriver Resort south of Bend is has decent fishing and reliable water temps. There is public lands access upstream from the state hatchery which is about at the midpoint on the river. Mostly big, wide and shallow flatwater and the fish will be buried in the stream bank grass.
4) If (and it is a big if..) you hit a cool or cloudy period, the BLM section of the Crooked River below Bowman Dam near Prineville is a nice Little J sized river with a wild redsides population that varies from good to fantastic depending on the year. Most of the fish are smaller though and you’ll catch a lot more under a foot than over. In the right years, there are piles of them though.
But If the weather is the usual sunny and hot, don’t bother with the Crooked. The fishing will s--- and you’ll be bitten by three rattlesnakes in the 90 minutes it takes you to die of heat stroke.
5) Even in August, the McKenzie is worth fishing. A very beautiful river and it stays cold. Try the section around Paradise Campground for mixed wild/stocked bows and cuts. Its all humpy/stimulator water and can be a lot of fun. The McKenzie tribs in the upper watershed can also fish good for smaller cutts, even in hot weather. One decent one is the South Fork of the McKenzie above Cougar Dam, but virtually any of them can be worth fishing.
All this info is contingent on how they are doing in general with the west coast drought, something that I haven’t kept track of. All in all, it might be better if you could go in mid September though...
