Portland, OR Ragweed Pollen
Ragweed pollen in Portland usually peaks around August to September, reaching Low at its worst. Portland's mild, wet climate gives it an early, drawn-out tree season and a famously heavy grass season, fed by the grass-seed farms of the Willamette Valley just to the south.
Ragweed is lighter here than back east but still turns up in late summer and early fall.
Ragweed in Portland today
Monday, July 27, 2026
Ragweed pollen by month in Portland
How ragweed usually runs across the year. The current month is outlined.
Managing ragweed season in Portland
If ragweed is your trigger, start a daily antihistamine like cetirizine (Zyrtec) or loratadine (Claritin) a week or two before the August to September peak, rather than waiting for symptoms. Keep windows closed on high-count mornings, shower and change clothes after time outside, and run the AC on recirculate in the car.
When symptoms don't ease with over-the-counter medicine, an allergist in Oregon can test whether ragweed is really what you react to and talk through longer-term options like allergy shots.
Sources
More pollen in Portland
- Portland grass pollen — peaks June.
- Portland alder pollen — peaks March.
- Portland birch pollen — peaks April.
- Portland pollen calendar — every allergen, month by month.
- Portland pollen count today — live tree, grass, and weed levels with a 5-day forecast.
- Oregon pollen season — the statewide calendar and other cities.
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Sign up for free alertsSeasonal pattern based on Oregon pollen data and local sources. Today's reading updated daily. MyPollenPal