See ebird link below for the details. The more common and a few highly sought after offshore species are listed below with a short note about seasons.
Long-tailed Jaeger
An Aug-Sept bird. Less common earlier in summer
Parasitic Jaeger
Late summer through October. Less common earlier in summer
Pomarine Jaeger
Unusual in winter. Frequent in summer, common Sept. to Oct
South Polar Skua
Common Aug-Oct. Can be seen earlier in summer.
Rhinoceros Auklet
Common
Tufted Puffin
A summer bird along coast, sometimes spotted offshore
Cassin's Auklet
Year-round, very common in late summer through fall
Parakeet Auklet
Winter target bird
Marbled Murrelet
Year-round, easier to spot in summer months with better ocean conditions
Pigeon Guillemot
Common summer bird, less common earlier in year
Common Murre
Common
Ancient Murrelet
Can be seen year-round, but more of a late fall winter bird.
Scripp's Murrelet
Sought after treasure, late summer fall
Black-legged Kittiwake
Common winter bird, harder to find in summer and fall.
Sabine's Gull
A late spring through fall bird. Large numbers can be seen on right day in late summer/fall.
Arctic Tern
Fall migrant
Common Tern
Fall migrant
Laysan Albatross
Becoming more common. Any season. Always a good bird to see.
Black-footed Albatross
A few can be spotted in winter but can be abundant in summer and fall.
Short-tailed Albatross
Highly sought after winter bird. It can be seen at any season.
Fork-tailed Storm-Petrel
Spring and summer but can be seen at any time of year.
Leach's Storm-Petrel
A spring bird, but we need more trips off southern Oregon to see numbers possible.
Northern Fulmar
Abundant in fall and winter. Can be seen year-round,
Murphy's Petrel
Spring off southern Oregon. target species.
Mottled Petrel
Scattered records winter through spring. Need to search more for this one offshore. More trips off southern Oregon needed. Rare.
Hawaiian Petrel
A summer bird being seen more often. Rare.
Cook's Petrel
Scattered records offshore spring and fall. Not enough trips off southern Oregon to know much more. Rare.
Pink-footed Shearwater
Similar to Sooty in seasons.
Flesh-footed Shearwater
Sought after fall visitor. One or two on a trip is a treat.
Buller's Shearwater
A late summer fall visitor. Can be abundant on a good day.
Sooty Shearwater
Rare in winter but huge number arrive summer and fall.
Short-tailed Shearwater
Fall and winter. Recently being seen in more numbers in fall.
Other birds seen: loons, cormorants, variety of more common gulls, migrating passerines, waterfowl and shorebirds.
Marine mammals (whales, dolphins, porpoises, sea lion, fur seal) .
Shark and sunfiish.
See the ebird link at top for the mega rarities.