Western Pacific Railroad Museum, Portola Pollen Forecast - Today, Tomorrow and the Week Ahead
Pollen Today
Today (11 October) pollen in Western Pacific Railroad Museum, Portola is low; mold (alternaria) and mold (cladosporium) are low.
Pollen Tomorrow
Tomorrow (12 October 2026) levels are similar to today.
7-Day Trend
Over the next week mugwort, ragweed, mold (alternaria), and mold (cladosporium) will increase; grass will remain stable.
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Pollen Risk
Today - 11 October
| 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) | None | 0/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | None | 0/100 |
| Ragweed (Ambrosia) | None | 0/100 |
| Mold (Alternaria) | Low | 6/100 |
| Mold (Cladosporium) | Low | 20/100 |
Tomorrow - 12 October
| 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) | None | 0/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | None | 0/100 | |
| Ragweed (Ambrosia) | None | 0/100 | |
| Mold (Alternaria) | Low | 2/100 | |
| Mold (Cladosporium) | Low | 7/100 |
Local Environmental Conditions
Around 54% of the area near this site in Portola is woodland, with some open grassland and built-up land. The damp ground beside running water nearby supports trees, shrubs and reeds, adding to local pollen. The surrounding woodland makes trees an important local pollen source. Grass pollen adds noticeably to the overall load.
The year opens with tree pollen, which is highest around mid-spring. From mid-spring, grass pollen rises to a peak around early summer before easing off by late summer. Weeds on open ground add a smaller late peak from early summer into early fall. Temperatures range from around freezing in the coldest month to around 25°C in the warmest, with most rain falling in the cooler months.
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Frequently Asked Questions About Pollen in California
Is pollen high in Portola right now?
Currently, there is no significant pollen in Portola.
Will pollen levels change in Portola tomorrow?
On 12 October 2026, pollen conditions in Portola will be similar to today with no significant pollen expected.
Is pollen expected to decrease in Portola this week?
According to the five-day outlook, ambrosia and artemisia pollen levels will increase later in the week.
Which pollen types are currently active in Portola?
On 11 October 2026, there are no significant pollen types in Portola.
When is pollen season in Portola?
How often is the Portola pollen forecast updated?
The Portola pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Portola 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 Portola 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 Portola, 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 pollen scores represent risk levels, not direct pollen measurements. Higher scores indicate higher risk.
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).
