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NC summer steelhead can be distinguished from other steelhead by their run timing, life histories, genetic variation, maturation while in fresh water, and their preferred spawning habitat in higher-gradient habitats and small tributaries.

Little historical abundance information exists for NC summer steelhead. Abundance estimates today come mostly from volunteer snorkel surveys in headwater tributaries and mainstem rivers during summer months. The Eel River, which once supported the largest run of NC summer steelhead, has had decreasing adult returns over the last fifty years.

Summer steelhead migrate further inland into smaller tributaries than winter fish. They spend summer months resting in pools with consistent cool temperatures as they mature, waiting for winter rains to spawn in December-February. NC summer steelhead can tolerate water temperatures up to approximately 23°C (about 73°F) for short periods of time, but seek refuge in deep pools with cool seeps and springs. They prefer pools with boulders, large woody debris, and undercut banks that provide cover from predators and visual separation from other fishes. After spawning, adult fish migrate back to the Pacific Ocean around March. Juveniles leave their natal tributaries from April to June to feed and grow in mainstem rivers and estuary habitats before migrating to sea. Once at sea, most juveniles spend their first months near the coast before moving to the North Pacific Ocean to feed on krill, squid, fish, crustaceans, and amphipods in surface waters.

Recent studies found that NC winter and summer steelhead are distinct from one another. NC summer steelhead are more closely related to NC winter steelhead than they are to summer steelhead from other regions in California. NC summer steelhead have a genetic variation similar to spring-run Chinook salmon that influences run-timing to fresh water, which allows them to access higher elevation and smaller tributaries for spawning.