Princeton, New Jersey pollen forecast - today, tomorrow and the week ahead
Pollen Today
Today (20 September) pollen in Princeton, New Jersey is moderate; grass and ragweed are moderate; mugwort is low.
Pollen Tomorrow
Tomorrow (21 September 2026) ragweed remains moderate, grass 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 | 37/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | Low | 2/100 |
| Ragweed (Ambrosia) | Moderate | 48/100 |
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 | 24/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | None | 0/100 | |
| Ragweed (Ambrosia) | Moderate | 34/100 |
Local Environmental Conditions
Set on wooded suburban terrain in central New Jersey, Princeton's landscape is defined by oak and maple canopy alongside dogwood understory and landscaped campus lawns, the main contributors to seasonal pollen exposure. Wind patterns across the area help determine how far pollen travels from these source plants. Residents who spend time outdoors around Princeton typically notice the shift as each season turns over.
Princeton's tree pollen season begins with cedar and elm from late February with oak joining in and continuing through April. Grass pollen then peaks through May and June, and mugwort and nettle extend exposure into September. Humid summers in the mid-Atlantic favor a longer weed pollen tail into early autumn, a defining feature of the local season.
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Frequently Asked Questions About Pollen in New Jersey
Is pollen high in Princeton, New Jersey right now?
On 20 September 2026, overall pollen levels in Princeton, New Jersey are moderate. Grass is the main contributor to airborne pollen, while ambrosia and artemisia remain at lower levels
Will pollen levels change in Princeton, New Jersey tomorrow?
On 21 September 2026, pollen conditions in Princeton, New Jersey will be different from today, with ambrosia at moderate levels and grass continuing to decline
Is pollen expected to decrease in Princeton, New Jersey this week?
According to the five-day outlook, grass, ambrosia, and artemisia pollen levels will increase later in the week.
Which pollen types are currently active in Princeton, New Jersey?
On 20 September 2026, Grass is the dominant pollen source in Princeton, New Jersey. ambrosia and artemisia are also present but at lower levels.
When is pollen season in Princeton, New Jersey?
How often is the Princeton, New Jersey pollen forecast updated?
The Princeton, New Jersey pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Princeton, New Jersey 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 Princeton, New Jersey 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 Princeton, New Jersey, 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).
