Half Moon Bay pollen forecast - today, tomorrow and the week ahead
Today (9 August) pollen in Half Moon Bay is high; mugwort is high; grass and ragweed are medium. Tomorrow (10 August 2026) levels are similar - ragweed remains medium, grass declining, mugwort declining. Over the following five days grass, mugwort, and ragweed will increase. Forecasts are calculated by Airmine using satellites to map local vegetation and determine pollen season onset.
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Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team
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Half Moon Bay's setting on a foggy coastal terrace south of San Francisco supports coastal scrub, Monterey cypress, and artichoke and pumpkin farmland as the leading local vegetation, all factoring into the pollen count through the year. Wind patterns across the area help determine how far pollen travels from these source plants. As with most of the region, counts tend to build gradually rather than spike overnight.
Today - 9 August
-
Alder (Alnus):
None
0/100
-
Birch (Betula):
None
0/100
-
Hazel (Corylus):
None
0/100
-
Cypress (Cupressaceae):
None
0/100
-
Grass (Poaceae):
Medium
34/100
-
Willow (Salicaceae):
None
0/100
-
Mugwort (Artemisia):
High
54/100
-
Ragweed (Ambrosia):
Medium
44/100
High pollen levels may trigger sneezing, itchy eyes, and congestion. Airmine's neighbourhood estimates use satellites to map local vegetation and a statistical prediction model, updated four times daily.
Tomorrow - 10 August
-
Alder (Alnus):
None
0/100
-
Birch (Betula):
None
0/100
-
Hazel (Corylus):
None
0/100
-
Cypress (Cupressaceae):
None
0/100
-
Grass (Poaceae):
Low
22/100
-
Willow (Salicaceae):
None
0/100
-
Mugwort (Artemisia):
Medium
40/100
-
Ragweed (Ambrosia):
Medium
31/100
Air quality in Half Moon Bay
View air qualityFrequently Asked Questions
Is pollen high in Half Moon Bay right now?
On 9 August 2026, overall pollen levels in Half Moon Bay are high. Artemisia is the main contributor to airborne pollen, while ambrosia and grass remain at lower levels
Will pollen levels change in Half Moon Bay tomorrow?
On 10 August 2026, pollen conditions in Half Moon Bay will be different from today, with ambrosia at medium levels and artemisia, grass continuing to decline
Is pollen expected to decrease in Half Moon Bay 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 Half Moon Bay?
On 9 August 2026, Artemisia is the dominant pollen source in Half Moon Bay. ambrosia and grass are also present but at lower levels. cypress are not currently active.
When is pollen season in Half Moon Bay?
How often is the Half Moon Bay pollen forecast updated?
The Half Moon Bay pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Half Moon Bay 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 Half Moon Bay 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 Half Moon Bay, 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.
Want to see pollen forecasts for other cities in United States?
Check pollen in other popular cities:
Data provided by Airmine — Last update: 10 August 2026 at 02:34 CEST (Data is updated four times daily.)
This page provides the latest public pollen forecast for Half Moon Bay.
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Unless explicitly made clear, the content on this site has not been paid for by external organisations and is Airmine's sole responsibility.
Disclaimer: Forecasts are provided for informational purposes only and should not be relied upon as medical advice. Actual pollen and air quality conditions may vary from the forecast. If you have allergies, asthma, or another medical condition, consult a healthcare professional. Please see our Terms of Service for important information about limitations of liability.