Parts of Victoria are expected to face a moderate risk of thunderstorm asthma, health officials say.
A warning shows there may be a high pollen count or a severe thunderstorm in certain areas on Friday, the Health Victoria website shows.
Regions at moderate risk include the Central, North Central, Northern Country, North East and Gippsland areas.
People who may develop symptoms are urged to avoid exposure to storms or high winds, have a reliever on hand and know their asthma action plan.
Authorities are on high alert to issue warnings to the community after 10 people died in Melbourne during a rare thunderstorm asthma event in November 2016.
Thunderstorm asthma happens when a large group of people experience asthma, often triggered by high pollen levels mixed with weather conditions.