Philadelphia pollen forecast - today, tomorrow and the week ahead
Pollen Today
Today (12 September) pollen in Philadelphia is high; ragweed is high; grass is low.
Pollen Tomorrow
Tomorrow (13 September 2026) ragweed remains high, grass increasing, mugwort at low levels.
7-Day Trend
Over the next week grass, mugwort, and ragweed will decrease.
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Pollen Risk
Today - 12 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 | 25/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | None | 0/100 |
| Ragweed (Ambrosia) | High | 52/100 |
Tomorrow - 13 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) | Moderate | 44/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | Low | 13/100 | |
| Ragweed (Ambrosia) | High | 69/100 |
Local Environmental Conditions
Philadelphia's extensive green network, anchored by Fairmount Park and the Schuylkill River corridor, features oak, birch, and maple as the main tree pollen sources, with exposure varying between these green areas and the more built-up city centre. Surrounding Pennsylvania farmland and the Delaware River valley contribute additional grass and tree pollen, while the flat coastal plain allows pollen to disperse readily under prevailing westerly winds.
Philadelphia's pollen season opens with maple and elm from late February, followed by oak and birch through April and May. Grass pollen peaks through June and July, with ragweed contributing from August through September. The humid temperate climate means the season is well-defined and intense, while surrounding Pennsylvania farmland and the Delaware River valley contribute additional grass and tree pollen under prevailing westerly winds.
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Resource Hub
Pollen forecast neighborhoods 144 neighborhoods
Sports venues in Philadelphia 3 sports venues
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Frequently Asked Questions About Pollen in Pennsylvania
Is pollen high in Philadelphia right now?
On 12 September 2026, overall pollen levels in Philadelphia are high. Ambrosia is the main contributor to airborne pollen, while grass remain at lower levels
Will pollen levels change in Philadelphia tomorrow?
On 13 September 2026, pollen conditions in Philadelphia will be different from today, with artemisia at low levels, ambrosia at high levels and grass increasing
Is pollen expected to decrease in Philadelphia this week?
According to the five-day outlook, artemisia, grass, and ambrosia pollen levels are expected to gradually decrease, suggesting improving conditions later in the week.
Which pollen types are currently active in Philadelphia?
On 12 September 2026, Ambrosia is the dominant pollen source in Philadelphia. grass are also present but at lower levels. artemisia are not currently active.
When is pollen season in Philadelphia?
How often is the Philadelphia pollen forecast updated?
The Philadelphia pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Philadelphia 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 Philadelphia 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 Philadelphia, 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 exposure is expected to be minimal. |
| Low | 0-25 | Low risk of exposure. Small amounts of pollen may be present. |
| Moderate | 25-50 | Moderate risk of exposure. Pollen exposure is expected to be noticeable. |
| High | 50-75 | High risk of exposure. Elevated pollen exposure is expected. |
| Very High | 75-100 | Very high risk of exposure. Pollen 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).
