Portsmouth pollen forecast - today, tomorrow and the week ahead
Pollen Today
Today (20 September) pollen in Portsmouth is high; mugwort is high.
Pollen Tomorrow
Tomorrow (21 September 2026) mugwort declining.
7-Day Trend
Over the next week mugwort will increase; cypress, grass, and willow will remain stable.
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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) | None | 0/100 |
| Willow (Salicaceae) | None | 0/100 |
| Mugwort (Artemisia) | High | 54/100 |
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) | None | 0/100 | |
| Willow (Salicaceae) | None | 0/100 | |
| Mugwort (Artemisia) | Moderate | 48/100 |
Local Environmental Conditions
Residents in Portsmouth dealing with hay fever usually point to sycamore and oak as the culprits, particularly in spring near parks and gardens. Local farmland and hedgerows nearby add meaningful grass pollen through late spring and summer, especially under moist Atlantic fronts. Locals with allergies tend to plan around two peaks a year rather than one long stretch.
Locals in Portsmouth usually notice sycamore first, with oak not far behind it. Grass season overlaps a lot of this too, running May through September and peaking mid-summer. Sycamore pollen typically runs from April to June, before oak takes over, usually April to May. Worth factoring in if hay fever's ever been an issue for you here.
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Resource Hub
Pollen forecast neighborhoods 1 neighborhood
Local parkruns 16 parkruns
Local events 1 event
Frequently Asked Questions About Pollen in Portsmouth
Is pollen high in Portsmouth right now?
On 20 September 2026, overall pollen levels in Portsmouth are high. Artemisia is the main contributor to airborne pollen
Will pollen levels change in Portsmouth tomorrow?
On 21 September 2026, pollen conditions in Portsmouth will be different from today, with artemisia continuing to decline
Is pollen expected to decrease in Portsmouth this week?
According to the five-day outlook, artemisia pollen levels will increase later in the week.
Which pollen types are currently active in Portsmouth?
On 20 September 2026, Artemisia is the dominant pollen source in Portsmouth. cypress, grass, and willow are not currently active.
When is pollen season in Portsmouth?
How often is the Portsmouth pollen forecast updated?
The Portsmouth pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Portsmouth 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 Portsmouth 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 Portsmouth, 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).
