FleaDates › Flea season › California › San Diego
San Diego · CA
When does flea season start in San Diego?
San Diego doesn't get a real flea off-season — every month stays warm enough for fleas to keep breeding, heaviest Apr–Nov.
Ticks in San Diego
Local tick activity typically runs year-round, heaviest all year. The species to know in California: western blacklegged tick, American dog tick, brown dog tick.
More on species and timing: California tick season.
Numbers come from NOAA U.S. Climate Normals (1991–2020) recorded at SAN DIEGO BROWN FLD — a climate-based estimate; real years wobble.
Frequently asked questions
When does flea season start in San Diego?
It never fully stops — San Diego's monthly averages support flea activity essentially all year, with the heaviest stretch Apr–Nov.
Is flea season in San Diego different from the rest of California?
Not meaningfully — San Diego tracks the California statewide estimate closely. Both are climate-based estimates, so treat the edges as fuzzy, not exact.
Do dogs in San Diego need prevention outside flea season?
Yes — vets recommend year-round parasite prevention regardless of the local calendar. Indoor fleas ignore the weather entirely, and ticks in California are typically active year-round, a longer window than fleas get.