Rural insurer FMG has received 1700 claims relating to last week's violent storm, making it the costliest weather event for the company since the 2004 Manawatu floods.
The insurer will have to payout about $13.5 million but that figure could rise if more claims are lodged.
Most of the claims are from Canterbury farmers.
FMG marketing manager Glenn Croasdale says the damage is significant.
"In terms of scale, excluding the Canterbury earthquakes it would be our largest event in a long time," he says.
Mr Croasdale says the rate at which new claims are being lodged is starting to slow but as farmers get around their properties to assess the damage the insurer expects more claims to come in.
The claims mainly relate to farm buildings, vehicles and irrigators. There have been more than 200 irrigator claims so far, he says.
Mr Croasdale says FMG is working closely with the industry and local suppliers to try to fast-track the claims but there are some issues with getting enough parts for all the repairs needed.
Meanwhile, hundreds of homes in rural Canterbury still have no power more than a week after the storm hit.
Some 400 Orion and 45 MainPower customers remain without electricity.
The companies say they are working as quickly as they can, but the repairs are time consuming as power is restored to many of the properties one at a time.
