Forecast

Persistent heat and high grass pollen levels!

Sunshine and heat will continue to dominate the weather this week. Whilst these conditions do increase the risk of heat-induced thunderstorms, the weather forecast suggests these are only likely at the start of the week. Should it rain in Vienna, the pollen will be washed out of the air, thereby reducing levels slightly. However, increased lightning activity may lead to a sudden rise in pollen levels and trigger thunderstorm asthma.
Those with grass pollen allergies will be the most affected, as grass pollen is not only the main allergen in the ambient air, but these numerous pollen grains can also burst during thunderstorms, releasing free allergens into the air. 
The main sources of current pollen levels are couch grass, brome grass, as well as sweet vernal grass, tufted hairgrass, meadow grass, horse tail grass, crested dog’s-tail, tufted dog’s-tail and foxtail. In meadow areas, additional pollen levels may also be caused by sorrel and plantain.

Flowering cereal fields in the immediate vicinity can also cause additional pollen levels. However, as cereal pollen is significantly larger and heavier than the pollen of naturally occurring grasses, it is not carried very far by the wind.

Regionally, people who are sensitised to pollen from the olive family may need to expect low concentrations of olive and privet pollen in the air.

Sweet chestnut trees are also in flower and may trigger cross-reactions in people sensitised to beech or birch trees in the surrounding area.

The tree of heaven has largely finished flowering. This is a neophyte from Asia that spreads in nutrient-poor and dry habitats such as railway embankments or wasteland. Allergic skin reactions have already been documented.

In locations with particularly favourable climatic conditions, the first flowering specimens of mugwort have already been spotted. This marks the start of the herb pollen season in some areas. However, it will still be a few weeks before the plants are in full bloom across the board. Locally, however, there may already be low levels of allergic exposure.

The warm, humid weather is encouraging the release of fungal spores into the ambient air, which can already cause symptoms in many people with allergies.

In addition to the pollen types mentioned, bee balm, nettles, sourgrasses, legumes, grapevines and cypresses are also currently present in the pollen spectrum. However, these pose only a very low allergenic risk.