Thunderstorm asthma is a sudden asthma attack triggered by a thunderstorm during grass pollen season. It can affect people with hay fever who have never had asthma. Most people can lower their risk by being prepared before spring.

Emergency

Call triple zero (000) for an ambulance if you or someone with you has:

• sudden shortness of breath, or cannot speak properly
• a blue or grey reliever inhaler that is not helping
• blue or grey lips
• drowsiness, confusion or collapse

Tell the operator that it is an ASTHMA EMERGENCY. Start asthma first aid while you wait.

Key points

• Thunderstorm asthma happens when a storm hits on a day with high grass pollen. It can cause many people to have asthma attacks at the same time.
• In Australia, it happens in spring and early summer, mainly in the south-east.
• People with spring hay fever are at risk, even if they have never had asthma.
• In the 2016 Melbourne event, only about 1 in 4 people who went to hospital had been diagnosed with asthma.
• Following your asthma action plan, treating your hay fever and staying indoors before and during storms can lower your risk.
• A Doccy consultation can help with prescriptions for hay fever and asthma, if appropriate.

What is thunderstorm asthma?

Thunderstorm asthma is a sudden flare-up of asthma during or soon after a thunderstorm. It usually happens when pollen levels are high.

Three things need to come together:

• a high level of pollen in the air
• people who are allergic to that pollen, such as people with spring hay fever
• a thunderstorm with strong winds

Pollen grains are normally too large to get past your nose and throat. When they get wet from rain or very humid air, they swell and burst. Each grain breaks into hundreds of tiny particles. Strong winds from the storm push these particles down to ground level, where people breathe them in. They are small enough to reach deep into the lungs and make the airways tighten.

In south-eastern Australia, almost all events have been linked to ryegrass pollen.

How common is thunderstorm asthma in Australia?

Large thunderstorm asthma events are uncommon, but they can be severe. Australia has recorded at least 11 events, all in spring. Most have been in south-eastern Australia, including Victoria, New South Wales and the ACT.

The largest event in the world happened in Melbourne on 21 November 2016. Within 30 hours:

• there were 3,365 more emergency department visits for breathing problems than expected
• 476 more people than usual were admitted to hospital with asthma
• 35 people needed intensive care
• 10 people died

Only 28% of the people who went to an emergency department had current, doctor-diagnosed asthma. Their average age was 32. People of Indian, Sri Lankan or South-East Asian background were more likely to be affected.

Who is at risk?

You are at higher risk if you:

• have hay fever in spring, especially if you are allergic to ryegrass
• have asthma, especially if it is not well controlled
• have had asthma in the past
• get wheeze, cough or chest tightness in spring, even without a diagnosis
• are outside in the wind gusts just before a storm

Most people affected are young adults. Thunderstorm asthma can also affect children.

Symptoms

Symptoms can start within minutes of the storm front arriving. They include:

• wheeze, a whistling sound when you breathe
• tight chest
• shortness of breath
• a cough that will not stop

Hay fever symptoms, such as sneezing and itchy eyes, often come first or at the same time. Symptoms can get worse very quickly. Do not wait to see if they settle.

Asthma first aid

If someone is having an asthma attack, follow the National Asthma Council steps:

1. Sit the person upright and stay calm with them.
2. Give 4 separate puffs of a blue or grey reliever, using a spacer if you have one. Take 4 breaths after each puff.
3. Wait 4 minutes.
4. If they still cannot breathe normally, call triple zero (000). Keep giving 4 puffs every 4 minutes until the ambulance arrives.

You can call 000 at any time.

When to see a doctor

If you have any of the signs in the emergency box at the top of this page, call triple zero (000).

Get an urgent GP appointment, or call healthdirect on 1800 022 222 for advice, if:

• you have had an asthma attack, even if it settled
• you are using your reliever more than usual

See a GP if:

• you have spring hay fever and have never had your breathing checked
• you have asthma and want to review your asthma action plan or inhaler technique
• you get wheeze, cough or chest tightness in spring

How to lower your risk

Before pollen season

• See your GP to review your asthma action plan and check your inhaler technique.
• Use your inhalers regularly as prescribed by your doctor. Your doctor may suggest a preventer inhaler during this time if you do not already have one.
• Treat your hay fever. Steroid nasal sprays work best when used every day through the season. Read more about hay fever.
• Carry a reliever. If you have spring hay fever, ask your doctor or pharmacist whether you should carry one too.
• Learn asthma first aid.

On high-risk days

• Check the forecast. In Victoria, thunderstorm asthma forecasts run from 1 October to 31 December on the VicEmergency app and website.
• Stay indoors before and during storms, especially during the strong winds that come first.
• Close doors and windows, and turn off air conditioning that draws in outside air.
• Keep your asthma medicines with you, as set out in your asthma action plan.

Allergy treatment (immunotherapy) may also help. An Australian study found a grass pollen tablet reduced asthma symptoms during thunderstorm season. Talk to your GP if you would like a referral to an allergy specialist.

Read more about asthma.

How Doccy doctors can help

A Doccy consultation can help if you are an adult preparing for pollen season and have none of the warning signs on this page. A Doccy consultation can:

• prescribe a nasal spray or eye drops for hay fever, if it is appropriate
• continue a prescription for your usual asthma medicines, if it is appropriate
• provide a medical certificate if you need time off work or study, including time off during a thunderstorm because of your risk

A Doccy consultation is not suitable during an asthma attack. If you are having trouble breathing, follow asthma first aid and call triple zero (000). If you have had an asthma attack, see your GP in person for a review.

Resources and support

National Asthma Council Australia: information on thunderstorm asthma, asthma action plans and asthma first aid.

VicEmergency: thunderstorm asthma forecasts for Victoria from 1 October to 31 December.

Asthma Australia: information and support for people with asthma on 1800 278 462.

healthdirect: health information and a 24-hour nurse advice line on 1800 022 222.

These services and websites can provide extra information, but they do not replace advice from your own doctor.

1. National Asthma Council Australia. Thunderstorm asthma. 2024. https://www.nationalasthma.org.au/resources/thunderstorm-asthma
2. National Asthma Council Australia. First aid for asthma (adults and children over 12). https://files.nationalasthma.org.au/images/FAFA_12and-over_Web_2026-05-19-045831_ctqf.pdf
3. Victorian Department of Health. Epidemic thunderstorm asthma risk forecast. 2026. https://health.vic.gov.au/environmental-health/epidemic-thunderstorm-asthma-risk-forecast
4. Better Health Channel (Victoria). Thunderstorm asthma. https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/thunderstorm-asthma
5. Thien F, Beggs PJ, Csutoros D, et al. The Melbourne epidemic thunderstorm asthma event 2016: an investigation of environmental triggers, effect on health services, and patient risk factors. Lancet Planet Health. 2018;2(6):e255-e263. https://pubmed.ncbi.nlm.nih.gov/29880157/
6. Katelaris CH. Thunderstorm asthma: causes, risks and mitigation. MJA InSight+. 2026. https://insightplus.mja.com.au/2026/4/thunderstorm-asthma-causes-risks-and-mitigation