Victoria's wet winter sets up a dangerous spring for asthma and hayfever

Nine deaths. Three thousand per cent more people in intensive care. A city told to stay inside because the rain and the grass were about to combine into something a lot of lungs couldn’t handle. That was Melbourne on 21 November 2016, and it remains the world’s largest epidemic thunderstorm asthma event. It is not ancient history.

Meteorologists and health researchers are now flagging that Victoria’s 2026 spring pollen season looks more dangerous than last year’s. AirHealth CEO Dr Edwin Lampugnani reviewed satellite data showing abundant vegetation growth in the pasture regions northwest of Melbourne following what has been described as one of Victoria’s wettest winters in a decade. His assessment: conditions look “more favourable to a larger year than we did last year.” In 2025, Victoria recorded five extreme grass pollen days. The forecast for 2026 is more.

The grass pollen season opens 1 October. If you have patients with hayfever — and general practice sees a lot of them in September — now is the window to act.

---

What thunderstorm asthma actually is

Thunderstorm asthma is not just asthma triggered by cold air or rain. It is a specific mechanism: when a severe storm passes over an area with extreme grass pollen levels, the storm’s downdraft ruptures pollen grains into particles far smaller than whole pollen. Those fragments are small enough to bypass the nasal mucosa and penetrate deep into the lower airways, where they provoke an acute bronchospasm in sensitised individuals.

The critical feature — the one that makes this different from an ordinary asthma exacerbation — is that it affects people with no prior asthma history. During the 2016 Melbourne event, many of the people who experienced severe bronchospasm had no known asthma diagnosis. They had hayfever. They were outside or near open windows when the storm hit. The consequence was a 3,000% spike in asthma presentations to emergency departments and intensive care units across Melbourne in a single evening.

Nine people died. Most of them were not the high-acuity respiratory patients one might expect. They were people with hayfever who did not know they were at risk.

Melbourne earned what one researcher calls “hayfever capital of the world” status through a combination of geography — extensive ryegrass farming northwest of the city — and weather patterns that funnel pollen-laden northerly winds across the metropolitan area. The conditions that created one event in 2016 have not structurally changed.

---

The contested part

The risk is real. The precautionary case for action is strong. The tension is in how to communicate it without generating unwarranted anxiety about every overcast September afternoon.

Most spring days are not thunderstorm asthma events. Most hayfever sufferers will get through October and November with nothing worse than itchy eyes and a congested morning. Thunderstorm asthma events of the 2016 scale are rare. Communicating genuine risk without creating chronic anxiety in the significant proportion of Australians with allergic rhinitis is a clinical calibration challenge — and it belongs in the consultation room as much as it belongs in a public health warning.

The value of the Victorian Department of Health’s real-time thunderstorm asthma forecast is exactly this: it makes the warning specific rather than diffuse. On an ordinary spring day, no special action is needed. On a day when extreme pollen coincides with a forecast severe storm, there is specific guidance: stay indoors, keep windows closed before and during the storm, have your reliever inhaler with you. That kind of targeted advisory is more actionable — and less anxiety-inducing — than a seasonal blanket warning.

The gap, as always, is reaching the patients who do not know they need the information. The person with undiagnosed or poorly managed hayfever who has never thought of themselves as having a respiratory condition is the person the 2016 event killed. They were not in the system.

---

What to do before October

Update asthma action plans now. Any patient with known asthma or hayfever should have a written, current asthma action plan that names their reliever, their preventer (if prescribed), and exactly what to do in an acute episode. The season opens in nine days. An action plan written in October last year and not reviewed since is not the same as a current plan.

Recommend the Vic Emergency app. The thunderstorm asthma forecast sits within the Victorian Department of Health notifications framework and is accessible through the Vic Emergency app. For Melbourne patients especially, downloading the app and enabling notifications before 1 October is a five-minute action with real potential benefit. Many patients with hayfever who do not think of themselves as having asthma will not know this resource exists — they will not find it themselves in the middle of a storm.

Consider preventive therapy for moderate-to-severe seasonal sufferers. Patients who reliably struggle through September and October with poorly controlled hayfever — antihistamine not covering it, significant interference with daily function — are worth reviewing before the season starts rather than in the third week of October when they are symptomatic. An intranasal corticosteroid started two weeks before the season is more effective than one started after symptoms are established. Patients with a history of wheeze or chest tightness during pollen season warrant a low threshold for preventer therapy.

Know who to refer. Patients with severe hayfever, coexisting asthma, or previous thunderstorm asthma episodes warrant allergy or respiratory specialist review — not necessarily urgently, but before a high-risk event occurs. Sublingual immunotherapy, for eligible patients, is the one intervention that modifies the underlying allergic sensitisation rather than managing symptoms.

Victoria’s wet winter is done. The forecast is clearer now than it will be on the day a thunderstorm rolls in from the northwest. That is the window.

Verdict: yes — before 1 October, review hayfever and asthma patients, update action plans, and advise them about the thunderstorm asthma forecast service.

---

Sources cited

1. Wet winter increases risk of active hayfever season in Victoria — ABC Health, 22 September 2026
2. Thunderstorm asthma — Victorian Department of Health