Chloe WilsonAustralia's spring thunderstorm season is underway — and health authorities are warning that the window between October and December brings a danger most people don't associate with storms: a sudden, potentially fatal respiratory crisis triggered not by lightning or wind, but by pollen. With climate researchers at the Medical Journal of Australia noting in early 2026 that warming temperatures may be making these events more frequent and less predictable, this is the spring to get prepared before the next storm rolls in.
What Is Thunderstorm Asthma and Why Is It So Dangerous?
Thunderstorm asthma is not a metaphor. It is a documented medical phenomenon in which the updrafts of a severe thunderstorm rupture ryegrass pollen grains into particles so tiny — fragments up to 50 times smaller than a full pollen grain — that they bypass the nose and throat entirely and penetrate deep into the bronchial tubes of the lungs. For people with hay fever, even those who have never been diagnosed with asthma, these microscopic fragments can trigger a sudden, severe bronchospasm that comes on within minutes.
The mechanism is well understood. What makes it dangerous is the combination of scale and surprise. When a storm front hits a region with elevated grass pollen counts, thousands of people can be simultaneously affected in a matter of hours, overwhelming emergency services before most people even realise what is happening.
Southeastern Australia — particularly Victoria, southern New South Wales, and parts of South Australia — sits in the highest-risk zone globally for this event type. The ryegrass pollen season runs from October through December, and it peaks precisely when spring thunderstorms are most common.
Why Autumn 2026 Matters: A Warning Already in Place
NSW Health issued an alert for the 2025–2026 spring season identifying the greatest risk areas as southern NSW and the Riverina region, where ryegrass cover is heaviest. The peak higher-risk period was flagged as October to December — which means right now.
According to researchers writing in InSight+ (the Medical Journal of Australia's online journal) in February 2026, climate change is already influencing the length and intensity of grass pollen seasons in southern Australia. Longer pollen seasons mean a broader window of vulnerability — and less predictability about when any individual storm event will coincide with peak pollen loads.
This is not a theoretical risk. The reference event that reshaped emergency planning across Australia happened on the evening of 21 November 2016 in Melbourne.
The 2016 Melbourne Event: The Night 9,900 People Collapsed at Once
On the night of 21 November 2016, a severe thunderstorm moved across Melbourne during a peak ryegrass pollen day. Within 30 hours, emergency departments recorded 3,365 excess respiratory presentations — a 672 per cent rise above forecast. Ambulance Victoria logged 2,036 cases on the night itself, with triple-zero call volume running at 147 per cent above forecast between 9pm and midnight.
In total, 9,909 people presented to public hospital emergency departments across metropolitan Melbourne and Geelong, and 476 excess asthma-related hospital admissions were recorded. Between nine and ten people died, according to findings from the Victorian Coroner's investigation.
The most striking finding from the subsequent Lancet Planetary Health study was who the victims were. The worst-affected age group was not the elderly or the very young but adults aged 20 to 59. And critically, only 28 per cent of those affected had a current doctor-diagnosed asthma condition. The majority — more than 70 per cent — had not been told they were at respiratory risk. Many had hay fever. Some had seasonal allergies. Many had nothing at all on their medical record.
That finding changed the way health authorities communicate about this risk. You do not need an asthma diagnosis to be a victim of thunderstorm asthma.
If You Have Hay Fever, You Are in the Risk Group
The link between hay fever (allergic rhinitis) and thunderstorm asthma vulnerability is now well-established. When the immune system is sensitised to ryegrass pollen — which is what hay fever represents — it is already primed to mount a response. When microscopic pollen fragments reach the lower airways, that response can become a life-threatening bronchospasm even in someone who has never wheezed in their life.
Asthma Australia has urged anyone with hay fever or seasonal allergies to treat thunderstorm asthma preparedness as personally relevant — not just those who carry an inhaler. The organisation recommends that people with hay fever discuss a personalised Asthma Action Plan with their GP before the season, so that if an event occurs, they have medication on hand and know what to do.
For those already diagnosed with asthma, continuing preventer medication as prescribed is critical. Stopping preventers because "asthma feels fine" going into spring is a pattern doctors consistently warn against — the inflammatory baseline that preventers reduce is exactly what determines how severe a bronchospasm will be if one is triggered.
Concrete Case: What Happens When You're Caught Unprepared
Consider a realistic scenario that played out in thousands of variations on the night of 21 November 2016 — and that could easily recur this October or November.
Jamie, 34, works in graphic design in Melbourne's inner north. He's had hay fever since his mid-twenties — sneezing, itchy eyes, sometimes a scratchy throat during spring. He's never been diagnosed with asthma. He took antihistamines sporadically last spring but stopped in mid-October because he "felt fine." He doesn't own a reliever inhaler. His GP has never mentioned thunderstorm asthma.
On an afternoon in late October, pollen counts across Melbourne are rated "extreme" according to the Melbourne Pollen Count forecast from the University of Melbourne. A storm front is moving in from the northwest. Jamie, sitting at his home desk with a window open, starts to notice his chest feels tight. Within 20 minutes, he's struggling to breathe. He calls triple-zero but hold times are running at 8 to 12 minutes because of the simultaneous demand across the city.
If Jamie had seen his GP before spring and received a single-consultation assessment — which typically runs between $80 and $150 at a bulk-billing clinic, often fully covered under Medicare with a health care plan — he would likely have been prescribed a Ventolin reliever inhaler and given a written action plan. The cost of the reliever itself is $6.90 under the Pharmaceutical Benefits Scheme. The action plan would tell him: if a storm is approaching and pollen counts are high, go inside, close all windows and doors, take the reliever as a precaution, and call his GP if symptoms develop.
The difference between having the reliever and not having it, according to Victorian health data, was the single factor most associated with whether people in the 2016 event survived their bronchospasm without serious harm. Approximately 72 per cent of people who died or were critically ill had no reliever medication available to them.
A one-off GP consultation before the season peak — before you need it — costs under $150. The out-of-pocket cost of a single night in a public hospital after an emergency admission is typically $0, but the wait, the fear, and the systemic impact are not.
What To Do Before the Next Storm
Check the Melbourne Pollen Count forecast or your state's equivalent each morning through December. The University of Melbourne's AirRater app is widely recommended by health authorities for real-time pollen alerts. NSW Health and the Victorian Department of Health both publish daily pollen forecasts during the season.
Book a GP appointment now, not during a warning. Ask specifically about thunderstorm asthma risk. If you have hay fever, seasonal allergies, or a family history of asthma, you may be eligible for a Medicare-covered Asthma Management Plan. If your GP recommends a reliever inhaler, the PBS price is under $7.
On high-risk days, stay indoors during and immediately after storms. The highest concentrations of ruptured pollen particles occur in the 20 to 30 minutes before and during a storm front's arrival. Closing windows and doors, staying inside, and avoiding outdoor exercise on days when pollen counts are extreme and storms are forecast can significantly reduce your exposure.
Do not rely solely on antihistamines. Standard antihistamines treat upper-airway symptoms like runny nose and sneezing. They do not prevent bronchospasm in the lower airways. A reliever inhaler is the appropriate emergency response tool for thunderstorm asthma.
For people with existing respiratory conditions — including those who have been treated for smoke-related symptoms during bushfire seasons, which share some physiological overlap with thunderstorm asthma triggers — a health review before spring's peak is especially worthwhile. Bushfire smoke affects the lungs differently from pollen, but the underlying bronchial sensitivity it creates can compound your thunderstorm asthma risk.
The official resource for ongoing thunderstorm asthma advice and current-season warnings is Asthma Australia's thunderstorm asthma guidance page, which is updated throughout the season in coordination with state health departments.
The 2016 Melbourne event was described at the time as a once-in-a-generation disaster. Climate researchers are now warning that the conditions that produced it — a long pollen season, a dry spring, and a fast-moving storm — are becoming more common. The best time to see your GP about this was in September. The second-best time is today.
This article is for general informational purposes only and does not constitute medical advice. Always consult a registered GP or qualified health professional before making decisions about asthma management, medication, or your personal health plan.
