Letterkenny pollen forecast - today, tomorrow and the week ahead
Pollen Today
Today (20 September) pollen in Letterkenny is moderate; mugwort is moderate.
Pollen Tomorrow
Tomorrow (21 September 2026) mugwort increasing, grass at low levels.
7-Day Trend
Over the next week grass and mugwort will decrease; cypress 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) | Moderate | 35/100 |
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) | Low | 25/100 | |
| Willow (Salicaceae) | None | 0/100 | |
| Mugwort (Artemisia) | High | 60/100 |
Local Environmental Conditions
Letterkenny's River Swilly setting in the Donegal highlands features oak, ash, and birch as the main tree pollen sources, with exposure varying between riverside greenery and the built-up northern county-town centre.
Letterkenny sits along the River Swilly in County Donegal's northern hills, giving it a cooler, upland-influenced pollen season, with birch and hazel producing a moderately delayed spring bloom, while surrounding pastureland sustains a fairly typical grass pollen season, and mugwort and nettle along riverbanks and waste ground add a modest late-summer trickle.
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Frequently Asked Questions About Pollen in Donegal
Is pollen high in Letterkenny right now?
On 20 September 2026, overall pollen levels in Letterkenny are moderate. Artemisia is the main contributor to airborne pollen
Will pollen levels change in Letterkenny tomorrow?
On 21 September 2026, pollen conditions in Letterkenny will be different from today, with grass at low levels and artemisia increasing
Is pollen expected to decrease in Letterkenny this week?
According to the five-day outlook, grass and artemisia pollen levels are expected to gradually decrease, suggesting improving conditions later in the week.
Which pollen types are currently active in Letterkenny?
On 20 September 2026, Artemisia is the dominant pollen source in Letterkenny. cypress, grass, and willow are not currently active.
When is pollen season in Letterkenny?
How often is the Letterkenny pollen forecast updated?
The Letterkenny pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Letterkenny 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 Letterkenny 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 Letterkenny, 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. |
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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).
