Pollen is an important source of allergens in the natural environment, and the cause of the appearance of symptoms of allergic disease in hypersensitive individuals. In our laboratory, we monitor 60 types of pollen of various allergenic potential, and publish the results of measurements from different phytogeographical areas in Slovenia. Data on daily concentrations, together with many years of experience, are the basis for making short-term forecasts about pollen air pollution.

Pollen forecast

29 April – 6 May 2026

Rainfall and cooler weather have temporarily reduced airborne allergen levels in some areas. With more favourable weather conditions, pollen concentrations are expected to increase again.

In the lowlands, the main grass pollen season is underway. In dry and warmer weather, pollen loads will continue to rise. Plantain and sorrel are also releasing pollen.

Tree pollen (birch, hornbeam, hop-hornbeam, beech, and oak) still predominates in the air. Although concentrations are decreasing, they may still represent a significant trigger of allergic reactions. In the lowlands, the main flowering period is approaching its end, and a considerable proportion of airborne pollen originates from transport from higher altitudes and more distant regions. The plane tree season is in its second half, with locally elevated concentrations expected in urban environments where the tree is commonly planted. Pollen from manna ash, cypress/yew family, willow, walnut family, maple, elder, and locally horse chestnut will also be present. This year, conifers (spruce and pine) are flowering intensely and account for most of the yellow deposits observed on surfaces.

In the coastal region, grass pollen levels are moderate to high. Hornbeam and oak pollen loads may remain high until more substantial rainfall occurs, while birch and beech pollen loads will be moderate. The season of manna ash is ongoing, with allergens related to olive pollen. Pollen from plantain, sorrel, pellitory, plane tree, cypress, elder, and willow will be present. Larger amounts of conifer pollen (spruce and pine) are also expected.

Write to pelodinfo@nlzoh.si for more information.

Pollen calendar