Most of California has a defined window when bees are most active. San Diego doesn’t really work that way. The climate here is mild enough year-round that colonies stay alive through winter and build up faster than they would in colder regions. That said, there is a peak season - and knowing when it is gives you a head start.
The peak window: March through June
Spring is when honey bee colonies reach their maximum size after building through winter. When a colony gets too large for its current location, it splits. The old queen leaves with roughly half the bees to find a new home. That’s a swarm - and swarm season in San Diego typically runs from March through June, sometimes stretching into July.
During this window you’re most likely to see a swarm resting on a tree branch, fence post, or the side of a building. You’re also most likely to notice scout bees inspecting gaps in your eaves, stucco cracks, and roof penetrations. A swarm resting temporarily is different from a colony that has moved in. A swarm on a branch usually moves on within 24 to 48 hours. Scouts inspecting a wall cavity mean a colony is actively choosing your home.
Why San Diego is different
Two things make San Diego’s bee season longer and more active than most of California. First, the mild winters. Colonies don’t die back the way they do in colder climates - they keep building, which means they reach swarm size faster and more reliably. Second, Africanized honey bees are established throughout San Diego County. They swarm more frequently than European honey bees, establish colonies in smaller cavities, and are significantly more defensive once a colony is established.
You can’t tell an Africanized bee from a European honey bee by looking at it. That distinction matters when you’re deciding whether to handle a swarm situation yourself.
What to do if you see a swarm
If bees are clustered on a branch or fence and haven’t gone into a structure yet - give it 24 to 48 hours. A resting swarm that hasn’t found a home may move on. Keep people and pets away from the cluster but don’t spray it, disturb it, or try to move it. Disturbing a swarm can trigger a defensive response.
If bees are entering and exiting a gap in your wall, eave, or roof - that’s no longer a swarm situation. A colony has chosen your home. That requires removal, not waiting.
Year-round vigilance
Even outside peak season, San Diego homeowners should check their properties at least once a year - before spring if possible. Look for open eave ends, gaps in stucco, unscreened vents, and roof penetrations around pipes or conduit. Sealing potential entry points before scouts find them is always cheaper than removing a colony after they’ve moved in.
