The combined damage bill from two severe storms that struck Western Australia's largest regional city is yet to be fully finalised, with the clean-up expected to stretch well into July.

The initial tornado struck Bunbury, 200 kilometres south of Perth, on May 10, damaging more than 200 properties across the city's southern suburbs.

That system was followed by further severe storms on June 1 that destroyed 10 properties.

The combined damage from both systems has left a significant amount of debris still awaiting cleanup.

Bunbury Regional Prison was also hit hard by the tornado with two prisoner accommodation units rendered uninhabitable, resulting in 45 prisoners moved to other units or houses within the prison and a further 27 transferred to other prisons.

Minister Sue Ellery told parliament the valuation of facility's damages and the timeline of repairs have not yet been finalised. 

City of Bunbury chief executive Alan Ferris said the clean-up of the June 1 storm, which destroyed two homes and eight businesses, would take at least another three weeks to complete. 

After which, he said, the city would turn its attention to the trees still standing in the impacted areas to check if they were safe, and if found unsafe these would be considered for removal.

Mr Ferris said fallen and uprooted trees from the last two storms would be mulched and wood chipped to be used around the city where possible, while large tree trunks would be kept to be used in reserves and parks.

More than 100 relief applications

As of June 10, almost 150 applications for the Premier Relief Payment scheme had been approved for City of Bunbury residents impacted by the severe weather events over the past month.

The scheme allows for a $2,000 or $4,000 one-off payment for homes, which had received major or severe damage, respectively. 

A Department of Fire and Emergency Services (DFES) spokesperson said the majority of the 138 approved applications were in relation to property damage from the May 10 tornado which hit Bunbury. 

The DFES spokesperson said a further 39 applications were currently being assessed, with some related to the most recent storm on June 1.

They said once approved, payments were made within two to three business days. 

With most of the storm season still ahead the spokesperson clarified someone could be granted the relief payment again in the future if another storm were to strike.

"Applying for assistance under one activation for the Premier' Relief Payments scheme does not prevent that same person from making another application in the future under a different application."