Gilroy pollen forecast - today, tomorrow and the week ahead

Today (9 August) pollen in Gilroy is medium; mugwort and ragweed are medium; cypress and grass are low. Tomorrow (10 August 2026) levels are similar - mugwort remains medium, ragweed declining. Over the following five days cypress, grass, mugwort, and ragweed will increase. Forecasts are calculated by Airmine using satellites to map local vegetation and determine pollen season onset.

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Gilroy's parks, including Christmas Hill Park and the Uvas Creek corridor, feature oak, eucalyptus, and introduced trees as the main pollen sources, with exposure varying between these green areas and the more built-up city centre. Surrounding Santa Clara Valley farmland and the Diablo and Santa Cruz Mountain foothills contribute substantial grass and crop pollen, while the valley setting channels prevailing northwesterly winds and marine air from the San Francisco Bay.

Today - 9 August

  • Alder (Alnus):

    None

    0/100

  • Birch (Betula):

    None

    0/100

  • Hazel (Corylus):

    None

    0/100

  • Cypress (Cupressaceae):

    Low

    9/100

  • Grass (Poaceae):

    Low

    13/100

  • Willow (Salicaceae):

    None

    0/100

  • Mugwort (Artemisia):

    Medium

    47/100

  • Ragweed (Ambrosia):

    Medium

    36/100

High pollen levels may trigger sneezing, itchy eyes, and congestion. Airmine's neighbourhood estimates use satellites to map local vegetation and a statistical prediction model, updated four times daily.

Tomorrow - 10 August

  • Alder (Alnus):

    None

    0/100

  • Birch (Betula):

    None

    0/100

  • Hazel (Corylus):

    None

    0/100

  • Cypress (Cupressaceae):

    None

    0/100

  • Grass (Poaceae):

    None

    0/100

  • Willow (Salicaceae):

    None

    0/100

  • Mugwort (Artemisia):

    Medium

    30/100

  • Ragweed (Ambrosia):

    Low

    20/100

Air quality in Gilroy

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Frequently Asked Questions

Is pollen high in Gilroy right now?

On 9 August 2026, overall pollen levels in Gilroy are moderate. Ambrosia is the main contributor to airborne pollen, while artemisia, cypress, and grass remain at lower levels

Will pollen levels change in Gilroy tomorrow?

On 10 August 2026, pollen conditions in Gilroy will be different from today, with artemisia at medium levels and ambrosia continuing to decline

Is pollen expected to decrease in Gilroy this week?

According to the five-day outlook, ambrosia, artemisia, cypress, and grass pollen levels will increase later in the week.

Which pollen types are currently active in Gilroy?

On 9 August 2026, Ambrosia is the dominant pollen source in Gilroy. artemisia, cypress, and grass are also present but at lower levels.

When is pollen season in Gilroy?
Gilroy's pollen season opens with acacia and tree pollen from January in the mild Santa Clara Valley climate. Oak follows through March and April, with grass peaking strongly through April and May from the surrounding agricultural valley. The valley setting channels prevailing northwesterly winds and marine air from San Francisco Bay, while surrounding farmland and the Diablo and Santa Cruz Mountain foothills contribute substantial grass and tree pollen.
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.

Want to see pollen forecasts for other cities in United States?

Check pollen in other popular cities:

Data provided by Airmine — Last update: 10 August 2026 at 02:34 CEST (Data is updated four times daily.)

This page provides the latest public pollen forecast for Gilroy.

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Unless explicitly made clear, the content on this site has not been paid for by external organisations and is Airmine's sole responsibility.

Disclaimer: Forecasts are provided for informational purposes only and should not be relied upon as medical advice. Actual pollen and air quality conditions may vary from the forecast. If you have allergies, asthma, or another medical condition, consult a healthcare professional. Please see our Terms of Service for important information about limitations of liability.