Based on 1,690 research-grade iNaturalist observations in California, Common Dolphin is most often recorded in May; in California it behaves like a seasonal. It ranks #40 among mammals recorded in the state in our data.
Delphinus delphis
Common Dolphin in California by month
Bars show research-grade observations per month. They mix true seasonality with how often people are outdoors, so treat small numbers with caution.
Also seen in California in May

California Ground Squirrel

Eastern Fox Squirrel

Desert Cottontail
Coyote

Mule Deer
California Sea Lion

Western Gray Squirrel
Black-tailed Jackrabbit
Places to look in California
Botanical GardenThe Huntington Library, Art Museum, and Botanical Gardens
State ParkHearst Castle
Botanical GardenSan Francisco Botanical Garden
Anza-Borrego Desert State Park
Angeles National Forest
National ForestSequoia National Forest
FAQ
When does Common Dolphin appear in California?
Mainly January–November, with the most records in May.
How common is Common Dolphin in California?
It ranks #40 by number of iNaturalist observations among mammals in California (1,690 records in our sample).