Gilroy pollen forecast — Highway 152 Tree Row neighborhood
Pollen Today
Today (20 September) pollen in Highway 152 Tree Row, Gilroy is high; ragweed is high; grass is moderate; mugwort is low.
Pollen Tomorrow
Tomorrow (21 September 2026) levels are similar to today.
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 | 35/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | Low | 2/100 |
| Ragweed (Ambrosia) | High | 60/100 |
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) | Moderate | 35/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | Low | 2/100 | |
| Ragweed (Ambrosia) | High | 60/100 |
Local Environmental Conditions
Sycamore and alder line the water's edge here, releasing pollen that carries easily on the wind; this sits close to home here. Located close by, this area has a canopy of coast live oak and bay laurel, oak chief among them for pollen output here. Here, within the neighborhood's edge, a park where mown turf grass and ornamental trees add grass and ragweed pollen.
Average temperatures range from about 10°C in February to 18°C in August, and most of the 558 mm annual rainfall falls in the cooler months around February. Pollen activity typically picks up as temperatures climb out of the February low, from around March onward.
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Frequently Asked Questions About Pollen in California
Is pollen high in Gilroy right now?
On 20 September 2026, overall pollen levels in Gilroy are high. Ambrosia is the main contributor to airborne pollen, while grass and artemisia remain at lower levels
Will pollen levels change in Gilroy tomorrow?
On 21 September 2026, pollen conditions in Gilroy will be similar to today, with ambrosia at high levels, artemisia at low levels, grass at moderate levels
Is pollen expected to decrease in Gilroy 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 Gilroy?
On 20 September 2026, Ambrosia is the dominant pollen source in Gilroy. grass and artemisia are also present but at lower levels.
When is pollen season in Gilroy?
How often is the Gilroy pollen forecast updated?
The Gilroy pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Gilroy 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 Gilroy 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 Gilroy, 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. |
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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).
