I live in North Los Angeles, not near the ocean.
When to Plant Onion Sets in Calif. In the Fall
Certified GKH Gardening Expert
Look for short-day growing varieties, they need 10 to 12 hours of sunlight and will do well in Southern CA.
An onion's variety requirements determine the time to plant but you can plant most varieties between September and March.
Short-day varieties are planted November through January and you can expect a harvest in late spring to early summer.