Hay fever does not announce itself politely. For many of us, the arrival of spring is less about cherry blossom and more about a daily skirmish with the immune system. And once the bloom is on, knowing what is in the air, and how much, becomes a small but useful form of self-defence.
The meteoblue pollen forecast tools are built with that in mind. Whether you are checking your home town from the sofa or planning a weekend hike, you can see how the next few days are likely to play out before you reach for the antihistamines.
What is in the air, and where to look
The Air Quality & Pollen forecast shows hourly forecasts for the pollen species that cause the most trouble across Europe and the Mediterranean: grass, ragweed, birch and olive (depending on the location). The same panel includes the Common Air Quality Index, particulates such as PM2.5 and PM10, desert dust, and the main gaseous pollutants.
For a bigger picture, the meteoblue Weather Maps include all the aforementioned data, plus interactive pollen layers for each of the species computed at 12 km model resolution, overlaid with wind speed at 10 m. Watching a pollen plume drift with the wind is a quick reminder of why a still, sunny day after a long bloom can feel so much worse than a blustery one.
Why the weather, not just the bloom, matters
A single birch tree can produce up to five million pollen grains, and the wind takes its share of them a long way before they find a sinus to settle in. Most grains land within a few dozen metres of the parent plant. But the long-distance tail of the curve is dramatic. Ragweed pollen has been recovered from ships hundreds of kilometres out across the North Atlantic. Juniper pollen released in central Texas has been traced as far as Tulsa, some 800 km away, and on one striking occasion appears to have reached Ontario, more than 2,400 km from its source. A still afternoon downwind of a flowering forest can therefore feel just as bad as standing next to one.
Wind direction, humidity and temperature all shape how a given afternoon plays out. Counts tend to climb in warm, dry, breezy conditions, when warming air lifts grains off the ground and the wind disperses them. As the air cools in the evening, suspended grains drift back down. This phenomenon, known as a pollen shower, explains why so many allergic people feel a second flare-up after sunset.
Rain usually helps. Even a short drizzle rinses pollen out of the air. However, thunderstorms are the exception that keeps allergy sufferers awake: cold downdrafts can sweep pollen up into a storm cloud, where humidity, wind shear and lightning fragment intact grains into far smaller particles. Those fragments, small enough to bypass the upper airways and reach the lungs, can trigger sudden, severe asthma attacks in sensitised people. The effect, known as thunderstorm asthma, was responsible for the worst recorded event of its kind in Melbourne on 21 November 2016, when emergency services were overwhelmed at the peak of the grass pollen season.
A longer season than the one your parents knew
If you feel that hay fever has been getting worse, you are not just imagining it. The Lancet Countdown in Europe 2026 report found that the pollen season for birch, alder and olive starts one to two weeks earlier in 2015–2024 than it did in 1991–2000, which is a noticeably longer window of itchy eyes. A 50-year Swiss record reaches similar conclusions for hazel, birch and grass.
A small advantage, taken daily
Knowing that tomorrow morning's birch index will be high, or that a thunderstorm is brewing on a peak grass pollen day, is the difference between bracing for a potentially difficult afternoon, and being ambushed by one.
With high-resolution models, machine learning, and atmospheric data on a scale unimaginable a generation ago, it is now possible to equip allergy sufferers with a sharper picture of the air around them than ever before.
Got a question about how pollen behaves where you live, or want to compare notes with fellow sufferers? Visit the dedicated thread on the meteoblue Community Forum to ask our experts and swap tactics with the meteoblue community!
