OR pollen report
Portland Pollen Report
Portland sits at the north end of the Willamette Valley, the world's grass-seed capital, and its June grass pollen counts rank among the highest in the nation. Spring arrives early with alder and birch, and the metro's famously wet climate keeps mold spores in play for much of the year. For a city its size, Portland punches well above its weight in allergy misery.
Current report
Overall
ModerateSunny, Portland, OR
What drives allergies in Portland
Grasses: ryegrass and fescue (May – July)
The Willamette Valley's grass-seed fields release massive pollen loads in late May and June. Grass — not trees — is Portland's worst season, and the worst days coincide with hot east winds through the Columbia Gorge.
Trees: alder, birch, and oak (February – May)
Alder (Alnus) starts as early as February, followed by birch, ash, and Oregon white oak. Douglas-fir pollen is abundant but rarely a major allergen.
Weeds: a lighter fall (August – October)
Ragweed is present but less intense than in the Midwest; plantain and sorrel contribute through late summer.
Mold: nearly year-round
Portland's long rainy season keeps Alternaria and Cladosporium active most of the year, with peaks after fall rains and during midsummer field cutting.
Pollen patterns in Portland
In Portland, tree pollen — including Alder, Birch, Cedar — typically dominates from late winter through spring. Rye grass is the most common warm-season pollinator, and Plantain drives the largest fall pollen load.
Top trees
- Alder
- Birch
- Cedar
- Hazel
- Maple
Top grasses
- Rye
- Orchard
- Timothy
- Bentgrass
Top weeds
- Plantain
- Dock
- Nettle
Top molds
- Cladosporium
- Alternaria
- Penicillium
- Aspergillus
Portland pollen calendar
Typical monthly intensity across the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| tree | ||||||||||||
| grass | ||||||||||||
| weed | ||||||||||||
| mold |
Historical reports
Cities near Portland
Explore pollen activity in nearby cities reported by the PollyMap network.
Frequently asked questions
What is the pollen count in Portland today?
PollyMap publishes real, microscope-verified pollen counts for Portland — measured from physical air samples. The latest report on this page shows current tree, grass, weed, and mold levels.
Is the pollen count high in Portland right now?
In late May and June, Portland's grass pollen counts are among the highest in the country. Tree pollen is heaviest in March and April. The measured reports on this page show today's actual levels.
When is allergy season in Portland?
Tree pollen runs February–May, grass peaks in June, weeds carry into fall, and mold stays active through the wet months — which is most of the year.
Why is Portland's grass pollen so bad?
The surrounding Willamette Valley grows most of the nation's grass seed. When those fields pollinate in late spring, the pollen blankets the entire region, Portland included.
Are you an allergy clinic in Portland? Claim your territory on PollyMap.
PollyMap is a local authority-building tool for allergy clinics, ENT practices, and any clinic that offers allergy care. By becoming the Official PollyMap Partner for your part of Portland, your clinic gets credited on real pollen reports, receives ready-to-share weekly content, and becomes the go-to local expert patients trust.
We assign each partner a designated territory within the Portland metro — like a franchise territory. Portland has room for multiple partners, but once your area is assigned, it's locked to your clinic.
Portland already has active PollyMap partners — and more territories are still available. The best areas go to the first clinics that sign up.
Portland's east and west sides, Vancouver, Beaverton, and Lake Oswego each make natural PollyMap territories. The first allergy clinic to claim one becomes the credited pollen source for its area.
- Your clinic credited on every Portland pollen report
- Weekly real-sample reports and ready-to-share content under your brand
- Locked territory — competing clinics can't claim your area
- Become the go-to allergy expert in your part of Portland
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