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Portland · OR

When does flea season start in Portland?

Flea season in Portland typically runs late March to mid-November, peaking May–Sep.

Flea season late March to mid-November Peak May–Sep
January — Quiet February — Low March — Low April — Moderate May — High June — High July — Peak August — Peak September — Peak October — Moderate November — Low December — Quiet J F M A M J J A S O N D Portland Peak May–Sep

Ticks in Portland

Local tick activity typically runs year-round, heaviest Apr–Oct. The species to know in Oregon: western blacklegged tick, American dog tick, Rocky Mountain wood tick.

More on species and timing: Oregon tick season.

Numbers come from NOAA U.S. Climate Normals (1991–2020) recorded at PORTLAND INTL AP — a climate-based estimate; real years wobble.

Frequently asked questions

When does flea season start in Portland?

Around late March in a typical year, once local averages hold around 50°F. A warm spring pulls it earlier — prevention shouldn't wait for the calendar.

Is flea season in Portland different from the rest of Oregon?

Not meaningfully — Portland tracks the Oregon statewide estimate closely. Both are climate-based estimates, so treat the edges as fuzzy, not exact.

Do dogs in Portland 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 Oregon are typically active year-round, a longer window than fleas get.

Elsewhere in Oregon