Corvallis pollen forecast - today, tomorrow and the week ahead
Pollen Today
Today (20 September) pollen in Corvallis is high; ragweed is high; grass and mugwort are low.
Pollen Tomorrow
Tomorrow (21 September 2026) grass remains low, mugwort remains low, ragweed declining.
7-Day Trend
Over the next week ragweed will increase; grass and mugwort will decrease.
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Pollen Risk
Today - 20 September
| Pollen species | Level | Value |
|---|---|---|
| Alder (Alnus) | None | 0/100 |
| Birch (Betula) | None | 0/100 |
| Hazel (Corylus) | None | 0/100 |
| Cypress (Cupressaceae) | None | 0/100 |
| Grass (Poaceae) | Low | 22/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | Low | 23/100 |
| Ragweed (Ambrosia) | High | 56/100 |
Tomorrow - 21 September
| Pollen species | Level | Value | 7-Day Trend |
|---|---|---|---|
| Alder (Alnus) | None | 0/100 | — |
| Birch (Betula) | None | 0/100 | — |
| Hazel (Corylus) | None | 0/100 | — |
| Cypress (Cupressaceae) | None | 0/100 | — |
| Grass (Poaceae) | Low | 10/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | Low | 13/100 | |
| Ragweed (Ambrosia) | Moderate | 45/100 |
Local Environmental Conditions
Corvallis's Willamette Valley setting features Oregon white oak, bigleaf maple, and alder as the main tree pollen sources alongside the exceptionally significant ryegrass and fescue grass seed crops of the surrounding farmland. Exposure varies between the wooded Mary's Peak foothills to the west and the more built-up university commercial areas, while the Willamette River corridor provides significant local green space. The surrounding grass seed industry makes summer grass pollen exceptional here.
Corvallis's Willamette Valley setting in Oregon produces a season opening in January with alder before hazelnut and birch peak through March and April. Grass from surrounding Willamette Valley farmland peaks strongly through May and June before mugwort extends exposure into September. Corvallis sits in one of the world's most significant grass seed production regions, making the late spring grass season exceptionally intense compared to most US cities.
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Frequently Asked Questions About Pollen in Oregon
Is pollen high in Corvallis right now?
On 20 September 2026, overall pollen levels in Corvallis are high. Ambrosia is the main contributor to airborne pollen, while artemisia and grass remain at lower levels
Will pollen levels change in Corvallis tomorrow?
On 21 September 2026, pollen conditions in Corvallis will be different from today, with artemisia at low levels, grass at low levels and ambrosia continuing to decline
Is pollen expected to decrease in Corvallis this week?
According to the five-day outlook, artemisia and grass pollen levels are expected to gradually decrease, while ambrosia pollen will increase, suggesting mixed conditions later in the week.
Which pollen types are currently active in Corvallis?
On 20 September 2026, Ambrosia is the dominant pollen source in Corvallis. artemisia and grass are also present but at lower levels.
When is pollen season in Corvallis?
How often is the Corvallis pollen forecast updated?
The Corvallis pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Corvallis come from nearby or far away?
Studies show that most pollen exposure (often 70–90%) comes from nearby sources, such as local trees and vegetation. A good pollen forecast therefore depends on accurately representing local vegetation. Pollen can travel long distances, but this usually matters only early in the season or during specific wind events.
Are pollen levels in Corvallis based on measurements or forecasts?
Pollen data is often misunderstood. Most "pollen levels" are not real-time measurements, but forecasts.
Direct pollen measurements are typically delayed by 1-2 days because they require manual analysis. To show current conditions in Corvallis, modern forecasts combine recent measurements, weather data, and information about local vegetation.
This allows us to estimate pollen levels for today and the coming days, not just report the past.
Airmine’s atmospheric monitoring platform was developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team, using satellite and Earth observation technologies to improve emissions monitoring.
Understanding the Scale
The 0–100 scores represent risk levels, not direct measurements of pollen or air pollutant concentrations. Higher scores indicate higher risk. Pollen and air quality use different thresholds.
Pollen
| None | 0 | No or negligible risk of exposure. Pollen/mold exposure is expected to be minimal. |
| Low | 0-25 | Low risk of exposure. Small amounts of pollen or mold spores may be present. |
| Moderate | 25-50 | Moderate risk of exposure. Pollen/mold exposure is expected to be noticeable. |
| High | 50-75 | High risk of exposure. Elevated pollen/mold exposure is expected. |
| Very High | 75-100 | Very high risk of exposure. Pollen/mold exposure is expected to be at or near its highest levels. |
Get More in the Airmine Pollen app
Get 15-day pollen forecasts with morning, afternoon and evening detail, plus 5-day air quality forecasts. Explore interactive pollen risk maps, estimated pollen season start, route profiles and a symptoms diary.
Features and forecast availability vary by region. Currently covering Europe, the contiguous US, southern Canada, South Africa, Australia, Indonesia (Java & Bali), Brazil, Paraguay, Uruguay and the Buenos Aires area.
Developed with support from the European Space Agency (ESA) Business Applications and Space Solutions (BASS).
