How Pollen Forecasts Work
Pollen forecasts predict airborne pollen levels based on plant phenology (growth cycles), weather conditions, and historical data. Counts are measured in grains per cubic metre of air.
Pollen Season Calendar
| Season | Primary Pollen | Months |
|---|---|---|
| Early Spring | Tree pollen (birch, oak, cedar) | February-April |
| Late Spring | Grass pollen | May-July |
| Summer-Fall | Weed pollen (ragweed) | July-October |
| Variable | Mould spores | Year-round, peak in damp periods |
Weather and Pollen
| Weather Condition | Effect on Pollen |
|---|---|
| Warm, dry, windy | Highest pollen — wind carries it far |
| After rain | Pollen drops temporarily (washed out) |
| During rain | Thunderstorm asthma risk — rain breaks pollen into finer particles |
| Cool, damp | Lower pollen levels |
| High humidity | Moulds increase, tree/grass pollen decreases |
Pollen Count Levels
| Level | Grains/m³ (grass) | Symptoms |
|---|---|---|
| Low | 0-29 | Minimal for most people |
| Moderate | 30-59 | Sensitive individuals affected |
| High | 60-149 | Most allergy sufferers symptomatic |
| Very High | 150+ | Severe symptoms likely |
Practical Tips
- Check pollen counts in the morning before opening windows
- Pollen is highest in the early morning (5-10 am) — exercise later
- Shower and change clothes after outdoor activity
- Keep car and home windows closed on high-count days
- Dry laundry indoors during peak season
Check daily weather and plan around conditions on Weather Tomorrow.
Get tomorrow's forecast in your inbox
Free daily weather email. Choose your city, pick your time.
Subscribe — FreeRelated Articles
Weather Tips4 min
Running in Different Weather — A Complete Guide
Rain, heat, cold, wind — each weather condition changes your run. Here is how to adapt your pace, gear, and strategy.
Weather Tips4 min
Planning Outdoor Events Around Weather — A Practical Guide
Concerts, festivals, markets, and sports events all depend on weather. Here is how to plan smart and handle the unexpected.
Weather Tips4 min
Outdoor Wedding Weather Planning — The Complete Guide
Your outdoor wedding depends on weather. Here is how to plan for it, monitor it, and prepare backup options.