Victorians have been asked to prepare for a possible thunderstorm asthma outbreak, with authorities raising the risk to "moderate" in parts of the state.
Health authorities have warned of a moderate risk for "an epidemic thunderstorm asthma event" for the state's North Central and North East districts on Monday.
A Department of Health and Human Services spokesman said moderate was in the "plan and prepare stage" of the early-warning system, and there was no immediate danger.
But people in affected areas should check the thunderstorm warning app or VicEmergency for updates in case the situation changes, and have their asthma plan ready.
A thunderstorm asthma warning system was introduced in Victoria following the deaths of nine people last year from what experts said was the world's worst recorded asthma thunderstorm.
The traffic-light warning system was raised to moderate on Sunday for the North Central, Northern Country and Central districts, which includes Melbourne.