Method
How our pollen forecast works
We turn pollen and weather signals into a local, plain-English forecast: what is in the air, whether it is likely to travel, and what that means for the day ahead.
What we measure
The forecast groups pollen into grass, tree and weed. Those are the clearest top-level groups available across the forecast sources we use, and they are easy for people to recognise when symptoms flare.
How we make the local forecast
For each location, we geocode the town, city or postcode area, collect available pollen forecasts, and combine them with weather factors such as wind, rain and temperature. Rain can suppress airborne pollen, while warm, dry and breezy conditions can help pollen spread.
Why nearby places can differ
Pollen forecasts are modelled for an area rather than measured at a single front door. A city search gives a broad city forecast. A postcode search lets us choose a more local forecast area, so the heading may include the outward postcode, such as Cardiff CF10.