Mountain House pollen forecast - today, tomorrow and the week ahead
Pollen Today
Today (20 September) pollen in Mountain House 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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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 | 35/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | Low | 9/100 |
| Ragweed (Ambrosia) | High | 66/100 |
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 | 10/100 | |
| Ragweed (Ambrosia) | High | 69/100 |
Local Environmental Conditions
This area, just outside the immediate area, has a stretch of valley oak and cottonwood lines the water, feeding some of the season's tree pollen. Here, nearby, a nearby park's turf and ornamental trees layer grass and ragweed pollen onto the seasonal mix. As with most local readings, actual levels can vary somewhat with short-term weather swings.
Average temperatures range from about 9°C in January to 26°C in July, and most of the 451 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 1 neighborhood
Frequently Asked Questions About Pollen in California
Is pollen high in Mountain House right now?
On 20 September 2026, overall pollen levels in Mountain House are high. Ambrosia is the main contributor to airborne pollen, while grass and artemisia remain at lower levels
Will pollen levels change in Mountain House tomorrow?
On 21 September 2026, pollen conditions in Mountain House will be similar to today, with artemisia at low levels, grass at moderate levels, ambrosia at high levels
Is pollen expected to decrease in Mountain House 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 Mountain House?
On 20 September 2026, Ambrosia is the dominant pollen source in Mountain House. grass and artemisia are also present but at lower levels.
When is pollen season in Mountain House?
How often is the Mountain House pollen forecast updated?
The Mountain House pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Mountain House 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 Mountain House 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 Mountain House, 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).
