State College pollen forecast — Greentree neighborhood
Pollen Today
Today (20 September) pollen in Greentree, State College is high; ragweed is high; grass is moderate; mugwort is low.
Pollen Tomorrow
Tomorrow (21 September 2026) grass declining, ragweed declining, mugwort no longer expected.
7-Day Trend
Over the next week grass, mugwort, and ragweed will increase.
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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) | Moderate | 39/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | Low | 14/100 |
| Ragweed (Ambrosia) | High | 63/100 |
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 | 1/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | None | 0/100 | |
| Ragweed (Ambrosia) | Low | 25/100 |
Local Environmental Conditions
The riverbank shelters hazel and willow, two trees whose pollen travels readily on the breeze, just outside the immediate area. Nearby, within the local area, woodland dominated by oak and birch, with birch a leading regional tree-pollen allergen. Green space with maintained lawn and planted trees, both contributing to grass and ragweed counts, within the neighborhood.
The water-adjacent hazel and willow are early risers, leading off the pollen calendar, with a peak generally falling in late winter. The nearby oak and birch stands take the lead as spring progresses, typically landing in April and May. As spring turns to summer, grass pollen rises toward its June high, followed by ragweed's own peak stretch from mid-August into October.
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Resource Hub
Pollen forecast neighborhoods 7 neighborhoods
Sports venues in State College 1 sports venue
Frequently Asked Questions About Pollen in Pennsylvania
Is pollen high in State College right now?
On 20 September 2026, overall pollen levels in State College are high. Ambrosia is the main contributor to airborne pollen, while grass and artemisia remain at lower levels
Will pollen levels change in State College tomorrow?
On 21 September 2026, pollen conditions in State College will be different from today, with ambrosia, grass continuing to decline
Is pollen expected to decrease in State College this week?
According to the five-day outlook, ambrosia, artemisia, and grass pollen levels will increase later in the week.
Which pollen types are currently active in State College?
On 20 September 2026, Ambrosia is the dominant pollen source in State College. grass and artemisia are also present but at lower levels.
When is pollen season in State College?
How often is the State College pollen forecast updated?
The State College pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in State College 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 State College 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 State College, 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).
