Thunder Fever: How Thunderstorms Can Trigger Asthma Outbreaks

It’s a foreboding term that you’d be hard-pressed to find in any medical journal, but it describes a very real and, at times, dangerous phenomenon. Thunder fever, also known as thunderstorm asthma, refers to specific thunderstorm conditions that increase the risk for an asthma attack.

What’s the History of Thunder Fever and How Common Is It?

On November 21, 2016, a band of severe thunderstorms swept through Melbourne, Australia, triggering a rash of asthma attacks that resulted in 8 fatalities and more than 8000 hospitalizations.1

Months after the outbreak, the Queensland University of Technology issued a report to the Department of Health and Human Services (DHHS) in Victoria detailing published reports on thunderstorm asthma. A review of literature found that the 2016 outbreak wasn’t an isolated incident. There had been 10 reported outbreaks of this infrequent and seasonal occurrence in Australia and 12 additional outbreaks internationally since 1983. International outbreaks had been observed in the United States, the United Kingdom, Italy, Canada, Greece, Iran, and Saudi Arabia.2

What Causes Thunder Fever?

It wasn’t until fairly recently that scientists began to understand what causes thunderstorm asthma. It had been unclear why certain thunderstorm conditions put people with asthma at greater risk for an attack when rain typically helps wash away pollen. It had also been a mystery why areas dominated by rye grass pollens – a large pollen that typically becomes trapped in the nose and sinuses before reaching the lungs – were the areas being affected by these conditions.3

Researchers at the University of Georgia studied the 2016 outbreak in Australia to answer these questions. Their study, published in the Journal of Applied Meteorology and Climatology, showed that a specific airflow pattern was the culprit.4

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The investigators found that downdrafts of cold air concentrate pollen and mold spore particles before sweeping them into the high humidity of the clouds. They are then broken down into fragments small enough to bypass the nose and sinuses for the lungs. Finally, gusty winds redistribute the highly concentrated particles in the storm area. “A distinct characteristic of the event was the very strong downdraft winds that led to a gust front and the spreading of pollen fragments across the region,” the researchers concluded.

Should Thunder Fever Concern Your Patients Who Have Asthma?

While thunderstorm asthma remains a rare occurrence that requires a confluence of specific weather conditions and allergens, advising your patients to restrict their outdoor activity during thunderstorms may be wise. Moving forward, the authors of the study hope their model will help develop advance warning systems “aimed at the medical and public health communities as well as susceptible members of the population.”4


  1. ‘Thunderstorm asthma’ deaths in Melbourne rise to eight. BBC. November 29, 2016. Accessed April 17, 2019.
  2. Literature review on thunderstorm asthma and its implications for public health advice. Department of Health and Human Services Victoria. May 19, 2017. Accessed April 17, 2019.
  3. Can a thunderstorm trigger an asthma attack? American Lung Association. Updated August 13, 2018. Accessed April 17, 2019.
  4. Grundstein A, Shepherd M, Miller P, Sarnat SE. The role of mesoscale-convective processes in explaining the 21 November 2016 epidemic thunderstorm asthma event in Melbourne, Australia [published online May 3, 2017]. J Appl Meteorol Climatol. doi:10.1175/JAMC-D-17-0027.1