Oregon has variable elevations and climates. Weather varies greatly depending on the specific location. The Coast, Willamette Valley and Western Cascade mountains receive lots of precipitation during the Fall and Winter months, mainly in the form of rain. Higher elevations of the Western Cascades, the High Cascades and the smaller mountain ranges east of the Cascades are prone to below freezing temperatures and large snowfalls from November into April. Lower elevations in Central and Eastern Oregon receive meager amounts of precipitation, typically as snow during winter. By late spring, the high elevation snow has melted and most days the skies are clear and blue, besides for the occasional thunderstorm. Summer will bring warm and hot weather to low elevations while the higher elevations have very pleasant conditions. The transition into fall brings a return of cooler weather and precipitation. Due to the large variations in climate, the best time of year to fish in Oregon is largely dependent on the specific region.
Coastal
The coast has amazing opportunities for fly fishing for anadromous fish species. There’s some awesome winter steelhead fishing from January through March. Spring Chinook can be caught on the fly with the correct tackle. Late summer brings opportunities to target sea-run cutthroat trout in small streams and rivers. There are also a few rivers with summer steelhead runs. Fall and early winter is accompanied by runs of fall Chinook Salmon and a few steelhead.
Willamette Valley and Western Cascades
Similar to the coast, the Willamette Valley and Western Cascades are more well known for their anadromous fish. The winter brings great opportunities for winter run steelhead. Spring offers Chinook salmon runs. Certain rivers, like the McKenzie, have good trout fishing during the summer. Fall and early winter are great for targeting fall Chinook and summer steelhead.
High Elevation Mountains
The High Cascades and other mountain ranges across the state have amazing fishing opportunities. In the winter, most fisheries are either closed or frozen over. As soon as the ice thaws the lakes and streams in the mountains are full of hungry trout. Early summer is often just as good as the spring, if not better. By late summer, the fish are usually a bit more finicky but they're still hungry. Early fall brings a start to cool weather which begins to slow the fish down. The snow can be deep as soon as mid fall. The best fishing won’t start until the snow thaws.
Central and Eastern Oregon
Lower elevations in Central and Eastern Oregon have some of the most productive trout waters in the state. Winter typically has slower fishing than other seasons; however, there are a few rivers that have productive steelhead runs and the trout will bite on nymphs. Usually by March the fish begin to get more active. From mid spring to early summer, the fishing is very productive with surface and subsurface flies. Mid summer and late summer can bring hot temperatures to the region, which slows fishing a bit. Slightly cooler temperatures in early fall get fish back to their active feeding states. By late fall, cold temperatures slow fishing down slightly and nymphing is generally most productive.