One of the most searched questions during summer is simply: when will this end? The answer for UK hay fever depends entirely on which pollen or allergen triggers your symptoms, because the UK pollen season is not one event but a sequence of overlapping ones. Grass pollen, the main trigger for most sufferers, fades in July to early August. But for those sensitive to weed pollen or mould spores, symptoms can persist well into autumn. Here is the full 2026 end-date picture by allergen and region.
UK Pollen Season: A Sequence of Triggers
UK hay fever season 2026 runs from late February all the way through to October for some sufferers. The key seasons are:
- Tree pollen (February to May): alder, hazel, birch, oak, and plane. These are the early-season triggers, and most tree pollen sufferers improve significantly by late May.
- Grass pollen (May to August): the main event for around 95% of UK hay fever sufferers. It peaks mid-May through June in the south and into July in the north.
- Weed pollen (June to September): nettle, dock, mugwort, and plantain. Less widely discussed but affects many sufferers, particularly those whose symptoms continue beyond July.
- Mould spores (July to November): Alternaria and Cladosporium spores peak in late summer and autumn, particularly in humid UK conditions.
When Does Grass Pollen Season End in the UK? (2026)
For the majority of sufferers - those sensitive primarily to grass pollen - relief comes in July and August:
- Southern England (London, South East, South West): grass pollen typically drops below troublesome levels in late July, with symptoms largely resolved by early August.
- Midlands and East Anglia: the season ends mid-to-late July.
- Wales and Northern England: late July to mid-August.
- Scotland: grass pollen can persist into August in some areas, particularly the Central Belt and Highlands.
In 2026, with a warm spring, forecasters have indicated the grass pollen season may run slightly longer than average, with symptoms possibly persisting into mid-August across parts of Scotland.
Weed Pollen: The Hidden Autumn Allergy
If your symptoms persist into September and October, weed pollen is the likely culprit:
- Nettle (June to September): extremely common across UK gardens, parks, and roadsides.
- Dock (June to August): often overlooked, particularly prevalent in rural areas.
- Mugwort (July to September): less common but can cause severe symptoms, including Oral Allergy Syndrome cross-reactions with food.
- Plantain (April to September): a very prolonged season; plantain pollen is widespread in UK grassland.
For weed pollen sufferers, hay fever season may not end until the first frosts, typically late October in most of the UK.
Mould Spores: Year-Round but Peaking in Autumn
Mould spores are often mistaken for a late hay fever when they are actually a separate allergen. Alternaria and Cladosporium spores peak in the UK from July through October, particularly after wet summers - a common occurrence in Scotland and Wales.
Mould spores are also elevated indoors during autumn and winter, when heating is turned on and humidity fluctuates. People sensitive to mould often describe symptoms as a late-summer cold that never fully resolves until winter. If your symptoms seem to restart or worsen in September after improving in August, mould spores are the probable cause. An indoor air purifier with MERV-13 filtration captures mould spores (typically 10 to 30 microns) and can provide year-round relief alongside good humidity control.
How to Know When Your Season Is Over
The practical way to confirm your personal hay fever season has ended:
- Check the Met Office pollen forecast daily - your symptoms should closely track the forecast for your specific triggers.
- If pollen is rated low and your symptoms have resolved, your season is likely done.
- If symptoms persist despite low pollen, consider whether dust mite or mould sensitivity is continuing the pattern.
DEFRA UK-AIR data, which powers this site's pollen map, provides regional daily pollen measurements for grass, tree, and weed categories. Tracking this against your own symptom diary over a season or two gives you a precise picture of your personal allergy calendar - useful for planning antihistamine use and air purifier operation the following year.
Managing the Transition Out of Pollen Season
As outdoor pollen decreases, do not abruptly stop all hay fever management. Indoor allergens - particularly dust mites - increase their impact during autumn and winter as windows close and heating creates warm, humid bedroom conditions. This is also when mould spores can cause indoor problems if humidity is not managed.
Continue running your bedroom air purifier through autumn if you have dust mite or mould sensitivity, and replace the filter after a full summer of pollen filtration, which will have reduced its efficiency. A quiet, efficient unit such as the CleanAirKits Luggable XL 7-Fan (MERV-13, around 93% capture, up to 681 m3 per hour, under 35 dB) suits year-round use, with filters costing only a couple of pounds a year to run. Autumn is also a good time to review the season with your GP and plan ahead: allergy testing, a possible immunotherapy referral, and optimising your treatment for next year.
