Thunderstorm Asthma

During grass pollen season people may notice an increase in asthma and hay fever. Grass pollen season (October through to December) also brings the chance of thunderstorm asthma.

Thunderstorm asthma is thought to be triggered by a unique combination of high amounts of grass pollen in the air and a certain type of thunderstorm. For people who have asthma or hay fever this can trigger severe asthma symptoms.

When a large number of people develop asthma symptoms over a short period of time, related to high grass pollen and a certain type of thunderstorm, it is known as epidemic thunderstorm asthma. To learn more, visit the Epidemic thunderstorm asthma fact sheet.

During an epidemic thunderstorm asthma event, pharmacies may see an increase in the number of patients presenting with breathing difficulties. Members should keep themselves up to date with the latest conditions so that your pharmacy can be as prepared as possible for a thunderstorm asthma incident.


For up to date information on epidemic thunderstorm asthma risk, including the risk forecast, advice and warnings, visit the Vic Emergency thunderstorm asthma page or download the VicEmergency app from Google Play or the App Store and set up a 'watch zone'.

The epidemic thunderstorm asthma risk forecast, as well as up to date grass pollen count and grass pollen forecast information is available on the Melbourne Pollen Count and Forecast website or app (App Store or Google Play).

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Page last updated on: 08 May 2024