Colusa pollen forecast - today, tomorrow and the week ahead
Pollen Today
Today (20 September) pollen in Colusa 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 and ragweed will increase; mugwort 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 | 42/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | Low | 15/100 |
| Ragweed (Ambrosia) | High | 67/100 |
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 | 48/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | Low | 20/100 | |
| Ragweed (Ambrosia) | High | 70/100 |
Local Environmental Conditions
Colusa sits on flat rice-farming country along the Sacramento River, where the dominant vegetation is a mix of rice fields, riverside cottonwood, and valley oak woodlots, shaping the local pollen profile across the seasons. This mix of plant life is fairly typical for the wider area around Colusa. Microclimates within the area can shift the timing slightly from one neighborhood to the next.
Colusa's tree pollen season begins with olive and acacia from January with eucalyptus joining in and continuing through February. A grass pollen peak follows through March and April; sagebrush and mugwort extend exposure into early autumn. The Southern California Mediterranean climate advances the season, and onshore Pacific breezes can periodically disperse pollen, shaping conditions across the city.
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Resource Hub
Pollen forecast neighborhoods 3 neighborhoods
Frequently Asked Questions About Pollen in California
Is pollen high in Colusa right now?
On 20 September 2026, overall pollen levels in Colusa are high. Ambrosia is the main contributor to airborne pollen, while grass and artemisia remain at lower levels
Will pollen levels change in Colusa tomorrow?
On 21 September 2026, pollen conditions in Colusa will be similar to today, with ambrosia at high levels, artemisia at low levels, grass at moderate levels
Is pollen expected to decrease in Colusa this week?
According to the five-day outlook, artemisia pollen levels are expected to gradually decrease, while ambrosia and grass pollen will increase, suggesting mixed conditions later in the week.
Which pollen types are currently active in Colusa?
On 20 September 2026, Ambrosia is the dominant pollen source in Colusa. grass and artemisia are also present but at lower levels.
When is pollen season in Colusa?
How often is the Colusa pollen forecast updated?
The Colusa pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Colusa 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 Colusa 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 Colusa, 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).
