Long rivers that have good flows all the time get some of their summer/fall Steelhead coming in from the ocean any time after the '4th of July'.

This would be the long rivers like on the Sacramento drainage (Sac, Feather, Yuba, American, Stan...), the Klamath and Trinity, the Rogue, the Umpqua, and the Deschutes to name just a few.

In the warm months with bright sunlight you need to be after them very early and very late in the day with low light levels.