Napa pollen forecast — Sterling Vineyards neighborhood
Pollen Today
Today (20 September) pollen in Sterling Vineyards, Napa is moderate; grass and ragweed are moderate; mugwort is low.
Pollen Tomorrow
Tomorrow (21 September 2026) grass remains moderate, mugwort remains low, ragweed increasing.
7-Day Trend
Over the next week grass, mugwort, and ragweed 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 | 33/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | Low | 6/100 |
| Ragweed (Ambrosia) | Moderate | 49/100 |
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 | 46/100 | |
| Willow (Salicaceae) | None | 0/100 | — |
| Mugwort (Artemisia) | Low | 18/100 | |
| Ragweed (Ambrosia) | High | 62/100 |
Local Environmental Conditions
Sterling Vineyards is a wine country with valley oaks, olive trees, and acres of grapevines. Olive pollen is a major allergen here — trees bloom in May and June. Valley fog mornings give way to warm afternoons that launch pollen into the air.
Napa's regional pollen pattern holds at Sterling Vineyards, with acacia and oak first appearing in January with olive following close behind through February and March. Grass pollen rises through March and April, and light weed pollen continues into early autumn. A long dry summer follows the spring peak, holding pollen counts low until autumn rains return, consistent with the wider Napa area.
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Frequently Asked Questions About Pollen in California
Is pollen high in Napa right now?
On 20 September 2026, overall pollen levels in Napa are moderate. Ambrosia is the main contributor to airborne pollen, while grass and artemisia remain at lower levels
Will pollen levels change in Napa tomorrow?
On 21 September 2026, pollen conditions in Napa will be different from today, with artemisia at low levels, grass at moderate levels and ambrosia increasing
Is pollen expected to decrease in Napa this week?
According to the five-day outlook, ambrosia, artemisia, and grass pollen levels are expected to gradually decrease, suggesting improving conditions later in the week.
Which pollen types are currently active in Napa?
On 20 September 2026, Ambrosia is the dominant pollen source in Napa. grass and artemisia are also present but at lower levels.
When is pollen season in Napa?
How often is the Napa pollen forecast updated?
The Napa pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Napa 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 Napa 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 Napa, 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).
