Victorians have been warned to expect a tornado and potentially dangerous thunderstorm asthma conditions in a burst of wild weather on Thursday.

Premier Daniel Andrews urged Victorians to be prepared ahead of forecast thunderstorms and extreme pollen levels as the state experienced its warmest weather so far this spring.

The tornado warning came ahead of a severe thunderstorm warning for parts of western Victoria on Thursday afternoon. The weather bureau said damaging winds, large hailstones and heavy rain were likely in the Wimmera and Mallee regions.

“There is a high to extreme pollen outlook across Victoria in the coming days, while the potential for thunderstorms will raise the thunderstorm asthma risk to moderate to high for Victoria today,” the Bureau of Meteorology said.

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It followed a warning for an extreme thunderstorm asthma risk issued for the Wimmera on Wednesday afternoon that was later upgraded to include the Mallee region.

There are also moderate warnings for Victoria’s south-west, central (which includes Melbourne) and north-central regions.

State health authorities urged anyone who had asthma or hay fever, or who experienced wheezing, breathlessness, a feeling of tightness in the chest or a persistent cough, to keep reliever medication with them at all times. They were also urged to avoid the wind gusts ahead of storms by remaining inside, with doors and windows closed.

“Health and emergency services are monitoring the situation closely and are ready to respond,” the department said.

“People who have asthma or seasonal hay fever should review the asthma first aid steps.”

In November 2016, 10 Victorians died and thousands were affected by the world’s worst outbreak of thunderstorm asthma.

The severity of that event caught many Victorians off guard, including emergency responders.

Mr Andrews also urged Victorians to be prepared.

“You have to take it really, really seriously, and I know that many, many people do, but we’re all busy, and sometimes you can find yourself not quite up to date,” he said of asthma.

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Nor will it be the end of the wild weather, more rain, storms and even floods are due for multiple states and territories from Friday, including flooded areas in the Murray-Darling Basin.

The NSW SES has expanded its focus to flooded towns along major river systems across the state.

“Unsettled conditions are expected as the week goes on, which brings a high risk of severe storms,” the SES said on Thursday.

Authorities urged anyone along the Murrumbidgee River, including Narrandera, Darlington Point, Hay and Wagga Wagga, to prepare and check for road closures, with many already flooded.

Emergency services were also carrying out damage assessments in the flood-hit towns of Forbes and Condobolin along the Lachlan River.

SES Assistant Commissioner Dean Storey said it was understandable that people in flood-ravaged towns might be disheartened by the weather forecast.

However, it was important for those likely to be affected to be prepared.

“This time is more important than ever as we see areas reach flood levels they haven’t seen in almost 70 years,” he said.