San Diego pollen forecast — Rancho Bernardo HS's Baseball Diamond neighborhood
Pollen Today
Today (20 September) pollen in Rancho Bernardo HS's Baseball Diamond, San Diego is high; ragweed is high; grass is moderate; mugwort is low.
Pollen Tomorrow
Tomorrow (21 September 2026) grass remains moderate, ragweed remains high, 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 | 38/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | Low | 8/100 |
| Ragweed (Ambrosia) | High | 70/100 |
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 | 28/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | None | 0/100 | |
| Ragweed (Ambrosia) | High | 61/100 |
Local Environmental Conditions
Rancho Bernardo HS's Baseball Diamond is set in the Rancho Bernardo suburban landscape of northern San Diego County, with introduced olive, oak, and coastal sage scrub as the main surrounding pollen sources in this inland valley setting. Surrounding chaparral and the Santa Fe Valley landscape contribute substantial grass and scrub pollen, while the warm inland climate advances the season compared to coastal San Diego and mugwort extends into September throughout.
San Diego's regional pollen pattern holds at Rancho Bernardo HS's Baseball Diamond, with olive and acacia first appearing in January before eucalyptus peaks during February. Grass pollen rises through March and April, and mugwort extends exposure into September. Onshore Pacific breezes periodically clear the air, though inland valleys can still see elevated counts, consistent with the wider San Diego area.
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Frequently Asked Questions About Pollen in California
Is pollen high in San Diego right now?
On 20 September 2026, overall pollen levels in San Diego are high. Ambrosia is the main contributor to airborne pollen, while grass and artemisia remain at lower levels
Will pollen levels change in San Diego tomorrow?
On 21 September 2026, pollen conditions in San Diego will be different from today, with ambrosia at high levels, grass at moderate levels
Is pollen expected to decrease in San Diego 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 San Diego?
On 20 September 2026, Ambrosia is the dominant pollen source in San Diego. grass and artemisia are also present but at lower levels.
When is pollen season in San Diego?
How often is the San Diego pollen forecast updated?
The San Diego pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in San Diego 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 San Diego 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 San Diego, 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).
