UK Pollen Calendar: What's in Season, Month by Month
It's September, and fat hen is usually at its peak in the UK. Another 3 types are still in the air too, including grass (overall), nettle and mugwort.
These windows are what a typical year looks like; the weather nudges them earlier or later. For what's actually in the air today, check the live pollen count for London or find your city.
Trees
Trees get the season going. Alder and hazel can be shedding pollen in the depths of winter, birch — the one many hay fever sufferers notice most — peaks around April, and oak carries things into late May.
| Species | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Alder | in season | peak | peak | in season | ||||||||
| Hazel | in season | peak | peak | in season | ||||||||
| Elm | in season | peak | in season | |||||||||
| Poplar | in season | peak | in season | |||||||||
| Birch | in season | peak | in season | |||||||||
| Ash | in season | peak | in season | |||||||||
| Plane | peak | peak | ||||||||||
| Oak | in season | peak |
Grasses
Grass is the big one — the most common hay fever trigger in the UK. Its season stretches from May into September, and June and July are usually the roughest patch.
| Species | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Grass (overall) | in season | peak | peak | in season | in season | |||||||
| Cock's-foot | in season | peak | peak | in season | ||||||||
| Ryegrass | in season | peak | peak | in season | ||||||||
| Timothy grass | in season | peak | peak | in season |
Weeds
Weeds see the season out. Nettle and plantain get going in early summer; mugwort and fat hen then keep counts up well into October.
| Species | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Plantain | in season | peak | peak | in season | ||||||||
| Sorrel | in season | peak | in season | in season | ||||||||
| Nettle | in season | peak | peak | in season | ||||||||
| Mugwort | in season | peak | in season | |||||||||
| Fat hen | in season | peak | peak | in season |
When does pollen season start and end in the UK?
In a typical year, the UK pollen season runs from January right through to October — not as one long stretch, but as three overlapping waves. Trees go first: alder and hazel can be airborne in January, and birch peaks around April. Grass takes over from May to September, peaking in June and July. Weeds — nettle, mugwort, plantain and fat hen — bring up the rear, carrying the tail of the season into October. After that, the air stays fairly clear until the trees start up again in the new year.
The exact timing shifts by a few weeks from year to year with temperature and rainfall, and the south of England usually gets going before Scotland does. So treat this page as a guide rather than a forecast — for what's in the air right now, the live city forecasts have hourly, species-level data, updated every day.
How to use this calendar
Each row shows the months a pollen type is usually in the air in the UK, with its peak window in the darker shade. If your symptoms flare up at the same time every year, look down the current month's column — the active rows are your shortlist of likely culprits, and a pharmacist or GP can help you narrow it down from there. The season windows come from the same species data that powers our daily forecasts.