Portland, OR Grass Pollen
Grass pollen in Portland usually peaks around June, reaching Very High 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.
Grass is Portland's defining allergen. The Willamette Valley is one of the country's biggest grass-seed growing regions, and pollen climbs through May and June.
Grass in Portland today
Monday, July 27, 2026
Grass pollen by month in Portland
How grass usually runs across the year. The current month is outlined.
Managing grass season in Portland
If grass is your trigger, start a daily antihistamine like cetirizine (Zyrtec) or loratadine (Claritin) a week or two before the June 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 grass is really what you react to and talk through longer-term options like allergy shots.
Sources
More pollen in Portland
- Portland alder pollen — peaks March.
- Portland birch pollen — peaks April.
- Portland ragweed pollen — peaks August to September.
- 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.
Get Portland pollen alerts
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Sign up for free alertsSeasonal pattern based on Oregon pollen data and local sources. Today's reading updated daily. MyPollenPal