Folsom pollen forecast - today, tomorrow and the week ahead
Pollen Today
Today (20 September) pollen in Folsom 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 mugwort will increase; ragweed will decrease.
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Features and forecast availability vary by region.
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 | 45/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | Low | 9/100 |
| 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 | 37/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | Low | 1/100 | |
| Ragweed (Ambrosia) | High | 65/100 |
Local Environmental Conditions
Folsom's parks and the American River corridor feature oak, ash, and walnut as the main tree pollen sources, with exposure varying between these green areas and the more built-up city centre. Surrounding Sacramento Valley farmland and the Sierra Nevada foothill woodland contribute substantial tree and grass pollen, while the American River Parkway channels airflows and contributes additional local tree pollen exposure.
Folsom's pollen season opens with oak and walnut from late January in the mild Sacramento Valley foothills climate. Ash follows through February and March, with grass peaking strongly through April and May. The American River corridor and the Sierra Nevada foothill setting contribute additional tree pollen, while surrounding Sacramento Valley farmland contributes substantial grass and crop pollen. The hot, dry summer largely suppresses mid-season pollen.
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Frequently Asked Questions About Pollen in California
Is pollen high in Folsom right now?
On 20 September 2026, overall pollen levels in Folsom are high. Ambrosia is the main contributor to airborne pollen, while grass and artemisia remain at lower levels
Will pollen levels change in Folsom tomorrow?
On 21 September 2026, pollen conditions in Folsom will be similar to today, with ambrosia at high levels, artemisia at low levels, grass at moderate levels
Is pollen expected to decrease in Folsom 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 Folsom?
On 20 September 2026, Ambrosia is the dominant pollen source in Folsom. grass and artemisia are also present but at lower levels.
When is pollen season in Folsom?
How often is the Folsom pollen forecast updated?
The Folsom pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Folsom 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 Folsom 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 Folsom, 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).
