MLHD director Tracey Oakman issued the alert on Thursday morning, saying current high pollen counts and the predicted thunderstorms could increase the risk of asthma.

"If you know you have asthma carry your asthma puffer with you at all times and try to stay indoors with the windows and doors closed during the storm period," Ms Oakman said.

"Be aware that thunderstorm asthma can also affect people who have not had asthma before.

"If you have breathing difficulties call 000 or go to your nearest hospital Emergency Department."

To receive an SMS alert when the pollen counts are high and thunderstorms are predicted, go to https://science.csu.edu.au/asthma and register for alerts.