Thunderstorm asthma explained

We do not forecast thunderstorm asthma. During the season (1 October to 31 December) check the official Epidemic thunderstorm asthma risk forecast (Victorian Department of Health) and VicEmergency. In an emergency call 000.

Epidemic thunderstorm asthma happens when a particular kind of thunderstorm meets a day of high grass pollen. Whole grass pollen grains are too big to reach deep into the lungs, but storm conditions can break them into tiny fragments that can. Many people can have breathing trouble at once, including people who have never had asthma but do have hay fever.

Why Melbourne

South-east Australia has very high ryegrass pollen in late spring, and the pastures of western and northern Victoria lie upwind of Melbourne on hot northerly days. The best-known event was on 21 November 2016, ten years ago this season.

What SkyPollen shows

Our city pages show modelled grass pollen and where it is drifting from. That is background, not a warning. The official forecast combines pollen and storm forecasts and is the one to act on.