Ontario, Oregon pollen forecast - today, tomorrow and the week ahead
Pollen Today
Today (20 September) pollen in Ontario, Oregon is high; grass and ragweed are high; mugwort is moderate.
Pollen Tomorrow
Tomorrow (21 September 2026) levels are similar to today.
7-Day Trend
Over the next week grass, mugwort, and ragweed will decrease.
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Features and forecast availability vary by region.
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) | High | 52/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | Moderate | 35/100 |
| Ragweed (Ambrosia) | High | 70/100 |
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) | High | 52/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | Moderate | 35/100 | |
| Ragweed (Ambrosia) | High | 70/100 |
Local Environmental Conditions
Ontario's setting on an irrigated farming valley along the Snake River on the Idaho border supports irrigated onion and sugar beet fields, riverside cottonwood, and sagebrush foothills as the leading local vegetation, all factoring into the pollen count through the year. Seasonal timing here follows the broader regional pattern typical of this part of the country. Allergy sufferers in Ontario generally plan around this same recurring seasonal rhythm.
The pollen calendar in Ontario opens with alder and birch starting February with maple joining in and continuing through March and April. Grass pollen rises through May and June, and plantain and nettle stretch the season into September. The mild, wet Pacific Northwest climate and frequent spring rain periodically wash pollen from the air.
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Frequently Asked Questions About Pollen in Oregon
Is pollen high in Ontario, Oregon right now?
On 20 September 2026, overall pollen levels in Ontario, Oregon are high. Ambrosia is the main contributor to airborne pollen, while grass and artemisia remain at lower levels
Will pollen levels change in Ontario, Oregon tomorrow?
On 21 September 2026, pollen conditions in Ontario, Oregon will be similar to today, with ambrosia at high levels, artemisia at moderate levels, grass at high levels
Is pollen expected to decrease in Ontario, Oregon this week?
According to the five-day outlook, ambrosia, artemisia, and grass pollen levels are expected to gradually decrease, suggesting improving conditions later in the week.
Which pollen types are currently active in Ontario, Oregon?
On 20 September 2026, Ambrosia is the dominant pollen source in Ontario, Oregon. grass and artemisia are also present but at lower levels.
When is pollen season in Ontario, Oregon?
How often is the Ontario, Oregon pollen forecast updated?
The Ontario, Oregon pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Ontario, Oregon 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 Ontario, Oregon 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 Ontario, Oregon, 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).
