Thunderstorm asthma can be very serious for people with asthma.

Thunderstorm asthma events are believed to be triggered by an uncommon combination of high grass pollen levels and a certain type of thunderstorm, causing pollen grains from grasses to be swept up in the wind and carried long distances.

If grass pollen is a problem for you then thunderstorms in spring and summer may also affect you.

Some pollens can burst open and release tiny particles that are concentrated in the wind just before the thunderstorm. These small particles get further into the airways and can trigger asthma symptoms.

To avoid exposure, stay inside with the windows and doors closed until after the storm has passed.

People as risk of acute asthma flare-ups triggered by a thunderstorm include those with seasonal hay fever, current asthma, a history of asthma or undiagnosed asthma.

The risk of thunderstorm asthma is highest in adults who are sensitive to grass pollen and have seasonal hay fever (with or without known asthma). The worst outcomes are seen in people with poorly controlled asthma.

To reduce the risk of thunderstorm asthma where it is a known trigger, it is recommended to aim for optimum asthma management year-round. This means optimising preventer use during spring thunderstorm season, controlling hay fever, checking pollen levels and avoiding exposure to pollen on these days where possible.


  • Understand the phenomenon
  • Have a written Asthma Action Plan (where advised by your doctor) and/or have practical knowledge of the 4 steps of Asthma First Aid
  • Have reliever medication available in grass pollen season and be aware of how to use it (ideally with a spacer)
  • Be alert to and act on the development of asthma symptoms as explained in your written Asthma Action Plan if you have one, or if you don’t, use Asthma First Aid
  • Be aware of thunderstorm forecasts particularly on HIGH or EXTREME pollen count days where possible avoid being outside during thunderstorms during the grass pollen season – especially in the wind gusts that come before the storm. Go inside and close your doors and windows and if you have your air conditioner on, turn it to recirculate. For thunderstorm asthma forecasts and alerts in Victoria go to the Vic Emergency website.
  • Never ignore asthma symptoms like breathlessness, wheezing and tightness in the chest. Start Asthma First Aid immediately and call Triple Zero (000) for help if symptoms do not get any better or if they start to get worse.

For up-to-date pollen levels in each state, visit the relevant site below:

Victoria, QLD, ACT and NSW: AusPollen website or app

Tasmania and ACT: AirRater website or app

If you find you are affected by thunderstorm asthma, follow our Asthma Emergency steps.