Letchworth Garden City pollen forecast - today, tomorrow and the week ahead
Pollen Today
Today (20 September) pollen in Letchworth Garden City is moderate; mugwort is moderate.
Pollen Tomorrow
Tomorrow (21 September 2026) levels are similar to today.
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) | Moderate | 30/100 |
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 | 50/100 |
Local Environmental Conditions
The nearby stretch of open moorland adds further grass and tree pollen exposure, particularly under southwesterly winds. On top of that, plane and lime are the two species driving most tree pollen in Letchworth Garden City, especially around parks and green corridors. It's a pattern shared by plenty of similarly sized towns nearby, shaped more by geography than anything unusual locally.
If you're wondering when hay fever kicks off in Letchworth Garden City, it's mostly down to plane and lime. You'll usually see plane pollen from around April through June, while lime follows on from May to July. Then grass pollen takes the baton from May all the way to September, usually peaking in June and July — that's when most people really feel it. Something to plan around if pollen usually gets to you.
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Frequently Asked Questions About Pollen in Hertfordshire
Is pollen high in Letchworth Garden City right now?
On 20 September 2026, overall pollen levels in Letchworth Garden City are moderate. Artemisia is the main contributor to airborne pollen
Will pollen levels change in Letchworth Garden City tomorrow?
On 21 September 2026, pollen conditions in Letchworth Garden City will be similar to today, with artemisia at moderate levels
Is pollen expected to decrease in Letchworth Garden City this week?
According to the five-day outlook, artemisia pollen levels will increase later in the week.
Which pollen types are currently active in Letchworth Garden City?
On 20 September 2026, Artemisia is the dominant pollen source in Letchworth Garden City. cypress, grass, and willow are not currently active.
When is pollen season in Letchworth Garden City?
How often is the Letchworth Garden City pollen forecast updated?
The Letchworth Garden City pollen forecast is updated four times daily. See the timestamp below for the most recent update.
Does pollen in Letchworth Garden City 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 Letchworth Garden City 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 Letchworth Garden City, 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).
