Santa Rosa pollen forecast - today, tomorrow and the week ahead
Pollen Today
Today (20 September) pollen in Santa Rosa is high; ragweed is high; grass is moderate.
Pollen Tomorrow
Tomorrow (21 September 2026) grass remains moderate, ragweed remains high, mugwort at low levels.
7-Day Trend
Over the next week grass and mugwort will increase; ragweed will decrease.
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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 | 28/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | None | 0/100 |
| Ragweed (Ambrosia) | High | 58/100 |
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 | 41/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | Low | 9/100 | |
| Ragweed (Ambrosia) | High | 70/100 |
Local Environmental Conditions
Santa Rosa's parks, including Howarth Park and the Santa Rosa Creek corridor, feature oak, eucalyptus, and madrone as the main tree pollen sources, with exposure varying between these green areas and the more built-up city centre. Surrounding Sonoma County wine country and coastal grasslands contribute substantial grass and tree pollen, while onshore Pacific winds can periodically disperse urban pollen across the valley.
Santa Rosa's pollen season opens with acacia and tree pollen from January in the mild Sonoma County climate. Oak follows through March and April, with grass peaking through April and May. The Sonoma Valley and surrounding wine country contribute substantial grass and tree pollen, while onshore Pacific winds can periodically disperse urban pollen. The dry summer largely suppresses mid-season pollen across the valley.
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Resource Hub
Pollen forecast neighborhoods 7 neighborhoods
Frequently Asked Questions About Pollen in California
Is pollen high in Santa Rosa right now?
On 20 September 2026, overall pollen levels in Santa Rosa are high. Ambrosia is the main contributor to airborne pollen, while grass remain at lower levels
Will pollen levels change in Santa Rosa tomorrow?
On 21 September 2026, pollen conditions in Santa Rosa will be different from today, with ambrosia at high levels, artemisia at low levels, grass at moderate levels
Is pollen expected to decrease in Santa Rosa this week?
According to the five-day outlook, ambrosia pollen levels are expected to gradually decrease, while artemisia and grass pollen will increase, suggesting mixed conditions later in the week.
Which pollen types are currently active in Santa Rosa?
On 20 September 2026, Ambrosia is the dominant pollen source in Santa Rosa. grass are also present but at lower levels. artemisia are not currently active.
When is pollen season in Santa Rosa?
How often is the Santa Rosa pollen forecast updated?
The Santa Rosa pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Santa Rosa 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 Santa Rosa 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 Santa Rosa, 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).
