A decade ago, on November 21, 2016, Melbourne and surrounding areas experienced the largest thunderstorm asthma event ever recorded anywhere in the world.
Thousands of people developed breathing difficulties, and 10 died. General practices, hospitals and emergency services were overwhelmed.
Thunderstorm asthma outbreaks are rare, but very serious. They are mostly likely between early October and late December. Ensuring that you, your staff, and your practice are able to respond effectively is very important.
What is thunderstorm asthma?
In people with an allergy to grass pollens, thunderstorm asthma can be triggered by exposure to a high concentration of pollen fragments in wind gusts at the start of a thunderstorm. In Victoria, this is associated with high perennial rye grass pollen counts.
Who is most at risk?
People with seasonal allergic rhinitis (hay fever) occurring in springtime, with or without known asthma, or confirmed hypersensitivity to rye grass pollen.
Diagnostically, they are likely to show a positive skin prick test or high ryegrass-specific IgE.
Others at risk are people with current asthma (especially if poorly controlled), a history of asthma, and who are not using an inhaled asthma preventer containing corticosteroids (ICS).
Environmental conditions
Thunderstorm asthma is triggered by exposure to rain, wind gusts and high volumes of airborne pollen, especially at the start of a thunderstorm.
The rain droplets crash into airborne pollen, breaking each grain into microscopic particles. When breathed in, these particles penetrate deep into the lungs and can trigger severe asthma symptoms.
What are the clinical guidelines for preventing thunderstorm asthma?
Patients with springtime allergic rhinitis (with or without asthma)
Advise them to:
- Check for alerts about high airborne pollen counts during spring, using a reputable source, such as the Australian Pollen Allergen Partnership.
- Check the Victorian Department of Health’s epidemic thunderstorm asthma risk forecast page, which provides three-day colour-coded advice through the season.
- Download the VicEmergency app from Google Play (opens in a new window) or the App Store (opens in a new window) and set up a watch zone.
- Remind them to avoid being outdoors at the start of and during thunderstorms in spring and early summer, especially during wind gusts that precede the rain front.
Educate those without asthma to recognise and report possible asthma symptoms such as wheeze, tight chest, dyspnoea, and to know how to access a rapid-acting reliever if needed.
Patients with asthma
Prescribe ICS-based preventer treatment as indicated. Current national asthma guidelines recommend ICS-containing treatment for all adults and adolescents who:
- have experienced asthma symptoms twice or more during the past month
- woken up due to asthma symptoms once or more during the past month
- have had an asthma flare-up in the previous 12 months.
For those allergic to grass pollens who are not already using ICS, prescribe preventive ICS-based treatment in springtime. Start at least two weeks before exposure to springtime high pollen concentrations and thunderstorms, and continue throughout the grass pollen season.
Update written asthma action plans regularly and ensure patients always have access to rapid-acting bronchodilator relievers.
All patients
Ensure at-risk patients are aware of their nearest urgent care clinic, and the contact details of the Virtual Emergency Department and Nurse-on-Call. Advise them to use these should they require urgent care after-hours or on weekends when the practice isn’t open.
Remind them to call 000 in an emergency.
Clinician resources
- The Victorian Department of Health epidemic thunderstorm asthma website contains risk forecasts, a campaign toolkit, and resources for health professionals.
- The National Asthma Council (NAC) has a free downloadable fact sheet for display and distribution to patients. It runs through symptoms and protective behaviours.
- The NAC also has a guide to the main intranasal treatment options for allergic rhinitis available in Australia, as of September 2026.
- Community HealthPathways Melbourne has several clinical resources for managing asthma and allergic rhinitis. They include:
What can your practice do to prepare for thunderstorm asthma?
- Consider having a clinical meeting to raise awareness of the condition, its diagnosis and its management.
- Display posters or information in your waiting rooms.
- Circulate the National Asthma Council Australia’s thunderstorm asthma information paper for health professionals to your clinical team.
- Use POLAR to identify patients with allergic rhinitis or asthma and offer them a thunderstorm asthma preventative appointment: POLAR walkthrough – thunderstorm asthma (.pdf) (Note: this resource is provided by Eastern Melbourne Primary Health Network. If you have any questions, please contact primarycare@nwmphn.org.au)
- Send out an SMS to all patients with asthma and allergic rhinitis with information on thunderstorm asthma with links to check for pollen alerts.
- Consider developing an asthma action plan with patients who have allergic rhinitis or rye grass pollen allergy despite no known asthma.
- Discuss and raise awareness of risks with patients who have asthma, allergic rhinitis, and ryegrass pollen allergy and check that they have access to preventers and relievers as part of their asthma plan.
