For the roughly 10 million people in the UK who suffer from hay fever (allergic rhinitis), the arrival of spring brings a familiar sense of dread. But "pollen season" isn't a single event. It actually comes in three distinct waves, each triggered by different plants releasing their pollen into the air.
Understanding this timeline is the first step in managing your symptoms effectively.
The Three Seasons of Pollen
1. Tree Pollen (Late March to Mid-May)
The season kicks off earlier than most people realise. As early as late February in some milder years, but typically peaking in April, trees are the first culprits. Birch pollen is the most common trigger in this category, affecting around 25% of UK hay fever sufferers. Other early bloomers include alder, hazel, and horse chestnut.
If you find yourself sneezing before the grass has even started to grow properly, tree pollen is likely your trigger.
2. Grass Pollen (Mid-May to July)
This is the big one. Grass pollen is the most common cause of hay fever in the UK, affecting an estimated 95% of sufferers. The season usually peaks in June and early July.
Unlike trees, which release pollen over a relatively short period, different grass species mature at different times, creating a prolonged season of misery. Days that are warm, dry, and breezy are particularly potent, as these conditions are perfect for keeping the fine grass pollen suspended in the air.
Pollen Level
High
Grass pollen levels often hit 'High' on warm, breezy days in June. This is when symptoms are most severe for the majority of sufferers.
3. Weed Pollen (Late June to September)
Just as the grass season begins to wane, weed pollen steps in to extend the suffering into autumn. Common culprits include nettles, dock, and mugwort. While fewer people are allergic to weed pollen compared to grass, it can cause severe symptoms for those who are sensitive.
Why Location Matters
It's also worth noting that the pollen season doesn't hit the whole country at once. Because pollen release is highly dependent on temperature and daylight hours, the season typically starts earlier in the south of England and gradually moves northwards, taking about three weeks to reach the north of Scotland.
Urban areas often experience "pollen traps" where buildings prevent the wind from dispersing the pollen, and pollution can actually make the pollen more allergenic by causing the grains to break open more easily.
Taking Control
The most powerful tool against hay fever is anticipation. If you know exactly what type of pollen triggers your symptoms, you can start taking preventative medication (like steroid nasal sprays or antihistamines) before the levels spike.
This is where the Achoo symptom diary comes in. By logging your symptoms daily—even just for a week—Achoo's AI can cross-reference your flare-ups with the specific breakdown of tree, grass, and weed pollen in your area. Very quickly, you'll learn exactly which of the three seasons is your personal nemesis, allowing you to prepare effectively next year.