Pollen Today in Leiden, The Netherlands
Current pollen levels, hourly forecast, allergy risk and outlook for Leiden, The Netherlands. Grass: Moderate · Mugwort: Moderate
Current Pollen Levels
grains/m³
Grass
MugwortSelect allergens for a personalized forecast
Pollen Outlook
grains/m³ peakGrassMugwortAbout Leiden
Today — Tomorrow
Local time (GMT+2)
Grass9 · Moderategrains/m³Mugwort10 · ModerateView detailed hourly pollen data
Detailed hour-by-hour pollen forecast for Leiden — today and tomorrow. Pollen concentrations per allergen type for each hour.
Today — Jul 20
| Hour | Grass | Mugwort |
|---|---|---|
| 00:00 | 7 | 7 |
| 01:00 | 9 | 8 |
| 02:00 | 10 | 8 |
| 03:00 | 8 | 9 |
| 04:00 | 7 | 7 |
| 05:00 | 8 | 7 |
| 06:00 | 8 | 7 |
| 07:00 | 7 | 8 |
| 08:00 | 9 | 6 |
| 09:00 | 7 | 5 |
| 10:00 | 7 | 5 |
| 11:00 | 8 | 4 |
| 12:00 | 8 | 4 |
| 13:00 | 7 | 4 |
| 14:00 | 6 | 3 |
| 15:00 | 6 | 3 |
| 16:00 | 6 | 3 |
| 17:00 | 6 | 3 |
| 18:00 | 7 | 3 |
| 19:00 | 7 | 4 |
| 20:00 | 7 | 4 |
| 21:00 | 10 | 7 |
| 22:00 | 9 | 10 |
| 23:00 | 10 | 10 |
Tomorrow — Jul 21
| Hour | Grass | Mugwort |
|---|---|---|
| 00:00 | 12 | 12 |
| 01:00 | 12 | 12 |
| 02:00 | 13 | 12 |
| 03:00 | 13 | 10 |
| 04:00 | 12 | 8 |
| 05:00 | 12 | 7 |
| 06:00 | 11 | 9 |
| 07:00 | 11 | 12 |
| 08:00 | 10 | 8 |
| 09:00 | 9 | 7 |
| 10:00 | 9 | 6 |
| 11:00 | 9 | 5 |
| 12:00 | 9 | 4 |
| 13:00 | 9 | 4 |
| 14:00 | 8 | 4 |
| 15:00 | 7 | 4 |
| 16:00 | 6 | 4 |
| 17:00 | 6 | 4 |
| 18:00 | 5 | 4 |
| 19:00 | 6 | 4 |
| 20:00 | 6 | 4 |
| 21:00 | 5 | 4 |
| 22:00 | 6 | 5 |
| 23:00 | 6 | 6 |
Pollen forecast in: Bruges · Zaanstad · Rotterdam
Planning outdoor activities? Check UV index in Leiden on UVI.today
What is the pollen level in Leiden today?
On July 20, Leiden reaches a peak pollen risk of Moderate around 23:00, driven mainly by Grass pollen. Live levels are tracked for birch, grass, alder, mugwort, olive, and ragweed.
Pollen snapshot
- Now
- Moderate
- Today's peak
- Moderate · 23:00
- Tomorrow's peak
- Moderate · 02:00
- Main allergen
- Grass
- Temperature
- 16°
About the Pollen Forecast
What is a pollen forecast?
A pollen forecast predicts the concentration of airborne pollen grains (measured in grains per cubic meter) for a specific location and time. Pollen is released by trees, grasses, and weeds during their pollination seasons. Higher concentrations trigger worse allergy symptoms in sensitive individuals. This forecast uses data from the Copernicus Atmosphere Monitoring Service (CAMS).
How do I check the pollen forecast today?
This page shows the live pollen levels for your location using data from CAMS via Open-Meteo. You get current pollen concentrations for birch, grass, alder, mugwort, olive, and ragweed — plus an hourly forecast chart and tomorrow's outlook. Select your allergens to see personalized risk levels.
When are pollen levels highest?
Pollen levels vary by type: tree pollen (birch, alder) typically peaks in spring mornings, grass pollen peaks in late spring and summer afternoons, and weed pollen (mugwort, ragweed) peaks in late summer and fall. Warm, dry, windy days have higher pollen counts. Rain temporarily reduces airborne pollen. Check the forecast chart above for today's exact pollen trend.
How can I reduce pollen exposure?
Many people reduce pollen exposure by keeping windows closed on high-pollen days, showering after time outdoors, and using air purifiers. Check the pollen forecast before outdoor activities, and consult a healthcare provider for personal advice.
What is an allergy profile?
Your allergy profile tells us which pollen types trigger your symptoms. Different people react to different pollens — some are allergic to birch and grass, others to ragweed or olive. By selecting your allergens, you get a personalized risk assessment that only considers the pollen types relevant to you, rather than a generic overall forecast.
Pollen risk levels
Risk levels are based on approximate pollen concentration thresholds per allergen type (grains/m³):
- Tree pollen (birch, alder): Low ≤10, Moderate ≤100, High ≤1000, Very High >1000
- Grass & weed pollen (grass, mugwort, ragweed): Low ≤5, Moderate ≤20, High ≤50, Very High >50
- Olive pollen: Low ≤10, Moderate ≤50, High ≤200, Very High >200
Your risk is the highest level among your selected allergens. These approximate thresholds are commonly referenced in European aeroallergen research (EAN) and clinical guidelines.
