The warning of a high risk of high levels of grass pollen applies during prolonged periods of stagnant weather, according to the Pollen Report website run by the Swedish Museum of Natural History.
It covers all of Götaland, large parts of southern and central Svealand - mainly in the eastern parts - and southernmost Norrland.
A warning for a milder, elevated risk prevails in a narrow strip north of these areas and a bit up along the southern Norrland coastline.
In the rest of Sweden, the risk of high levels is still small, but locally, near tall grass, it is greater.
In the northern inland areas of Norrland, there is a risk of high levels of birch pollen during prolonged periods of dry, sunny weather.
