Simi Valley pollen forecast — Reagan Presidential Library neighborhood
Pollen Today
Today (20 September) pollen in Reagan Presidential Library, Simi Valley is high; grass and ragweed are high; mugwort is low.
Pollen Tomorrow
Tomorrow (21 September 2026) mugwort remains low, grass declining, ragweed declining.
7-Day Trend
Over the next week grass, mugwort, and ragweed will increase.
Explore Forecasts
Get More in Our App
Local pollen and air quality forecasts, interactive pollen maps and route profiles
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) | High | 59/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | Low | 17/100 |
| Ragweed (Ambrosia) | High | 62/100 |
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 | 43/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | Low | 2/100 | |
| Ragweed (Ambrosia) | Moderate | 47/100 |
Local Environmental Conditions
Reagan Presidential Library is a southern California inland valley with coastal sage scrub and chaparral. Warming temperatures and Santa Ana winds spread pollen from the hills. Spring flowering is dramatic after wet winters — sage, ceanothus, and wild mustard.
Reagan Presidential Library tracks Simi Valley's broader pollen pattern, with olive and acacia appearing from January with eucalyptus following close behind through February. Peak grass pollen arrives in March and April, and light weed pollen carries into September. Onshore Pacific breezes periodically clear the air, though inland valleys can still see elevated counts throughout the year.
Get pollen & AQ on Strava
Follow your environmental exposure and performance with the free Airmine-Strava integration. See your pollen and air quality exposure for every Strava activity.
Resource Hub
Pollen forecast neighborhoods 6 neighborhoods
Sports venues in Simi Valley 1 sports venue
Frequently Asked Questions About Pollen in California
Is pollen high in Simi Valley right now?
On 20 September 2026, overall pollen levels in Simi Valley are high. Ambrosia is the main contributor to airborne pollen, while grass and artemisia remain at lower levels
Will pollen levels change in Simi Valley tomorrow?
On 21 September 2026, pollen conditions in Simi Valley will be different from today, with artemisia at low levels and ambrosia, grass continuing to decline
Is pollen expected to decrease in Simi Valley this week?
According to the five-day outlook, ambrosia, artemisia, and grass pollen levels will increase later in the week.
Which pollen types are currently active in Simi Valley?
On 20 September 2026, Ambrosia is the dominant pollen source in Simi Valley. grass and artemisia are also present but at lower levels.
When is pollen season in Simi Valley?
How often is the Simi Valley pollen forecast updated?
The Simi Valley pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Simi 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 Simi 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 Simi 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).
