Portola Valley pollen forecast — Tip Toe Falls neighborhood
Pollen Today
Today (20 September) pollen in Tip Toe Falls, Portola Valley is low; grass and ragweed are low.
Pollen Tomorrow
Tomorrow (21 September 2026) grass remains low, ragweed remains low, mugwort at low levels.
7-Day Trend
Over the next week mugwort and ragweed will increase; grass 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) | Low | 9/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | None | 0/100 |
| Ragweed (Ambrosia) | Low | 10/100 |
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 | 18/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | Low | 5/100 | |
| Ragweed (Ambrosia) | Low | 20/100 |
Local Environmental Conditions
Nearby, close by, sycamore and alder crowd the water's edge, typical of this area's coastal streamside woodland. Located nearby, this area has forest where coast live oak and madrone make up much of the canopy, driving local spring pollen counts. Surrounding neighborhoods with similar tree cover typically see a closely comparable pollen mix.
Average temperatures range from about 9°C in January to 20°C in August, and most of the 589 mm annual rainfall falls in the cooler months around January. Pollen activity typically picks up as temperatures climb out of the January low, from around February onward.
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Pollen forecast neighborhoods 3 neighborhoods
Frequently Asked Questions About Pollen in California
Is pollen high in Portola Valley right now?
On 20 September 2026, overall pollen levels in Portola Valley are low. Ambrosia is the main contributor to airborne pollen, while grass remain at lower levels
Will pollen levels change in Portola Valley tomorrow?
On 21 September 2026, pollen conditions in Portola Valley will be different from today, with ambrosia at low levels, artemisia at low levels, grass at low levels
Is pollen expected to decrease in Portola Valley this week?
According to the five-day outlook, grass pollen levels are expected to gradually decrease, while ambrosia and artemisia pollen will increase, suggesting mixed conditions later in the week.
Which pollen types are currently active in Portola Valley?
On 20 September 2026, Ambrosia is the dominant pollen source in Portola Valley. grass are also present but at lower levels. artemisia are not currently active.
When is pollen season in Portola Valley?
How often is the Portola Valley pollen forecast updated?
The Portola Valley pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Portola Valley 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 Valley 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 Valley, 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).
