Rancho Cucamonga pollen forecast - today, tomorrow and the week ahead
Pollen Today
Today (20 September) pollen in Rancho Cucamonga is high; ragweed is high; grass is moderate; mugwort is low.
Pollen Tomorrow
Tomorrow (21 September 2026) ragweed remains high, 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 | 47/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | Low | 12/100 |
| 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) | Low | 23/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | None | 0/100 | |
| Ragweed (Ambrosia) | High | 54/100 |
Local Environmental Conditions
Rancho Cucamonga's parks, including Central Park and the Cucamonga Creek corridor, feature oak, sycamore, and introduced eucalyptus as the main tree pollen sources, with exposure varying between these green areas and the more built-up city centre. Surrounding Inland Empire chaparral and the San Gabriel Mountain foothills contribute substantial grass and scrub pollen, while Santa Ana winds can concentrate pollen across the area.
Rancho Cucamonga's pollen season opens with acacia and native oak from January in the mild Inland Empire climate. Sycamore and grass follow through March and April, with the season peaking earlier than most US cities. The San Gabriel Mountain foothills channel airflows and concentrate pollen, while surrounding chaparral contributes substantial scrub pollen. Santa Ana winds can concentrate pollen across the area under offshore conditions.
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Pollen forecast neighborhoods 3 neighborhoods
Frequently Asked Questions About Pollen in California
Is pollen high in Rancho Cucamonga right now?
On 20 September 2026, overall pollen levels in Rancho Cucamonga are high. Ambrosia is the main contributor to airborne pollen, while grass and artemisia remain at lower levels
Will pollen levels change in Rancho Cucamonga tomorrow?
On 21 September 2026, pollen conditions in Rancho Cucamonga will be different from today, with ambrosia at high levels and grass continuing to decline
Is pollen expected to decrease in Rancho Cucamonga 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 Rancho Cucamonga?
On 20 September 2026, Ambrosia is the dominant pollen source in Rancho Cucamonga. grass and artemisia are also present but at lower levels.
When is pollen season in Rancho Cucamonga?
How often is the Rancho Cucamonga pollen forecast updated?
The Rancho Cucamonga pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Rancho Cucamonga 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 Rancho Cucamonga 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 Rancho Cucamonga, 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).
