"A high-risk of epidemic thunderstorm asthma is forecast in the Mallee, South West and Wimmera districts tomorrow," the department said on social media.

"This is the first high risk of the season and a good reminder to be prepared."

Thunderstorm asthma is thought to be triggered by a unique combination of high amounts of grass pollen in the air and a certain type of thunderstorm.

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For people who have asthma or hay fever this can trigger severe asthma symptoms.

When a large number of people develop asthma symptoms over a short period of time, related to high grass pollen and a certain type of thunderstorm, it is known as epidemic thunderstorm asthma.

Some ways the risk of of thunderstorm asthma can be minimised include:

In a statement on social media, the SES's Ararat Unit cautioned those who may be susceptible to thunderstorm asthma.

"Please ensure that you look out for yourselves and others. Seek medical attention when you feel like you are experiencing symptoms," the statement read.

Stay alert using the VicEmergency app and refrain from being outdoors during high periods of strong wind.

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