Lloyd's of London underwriter Hiscox said it now estimates net claims for Hurricanes Harvey, Irma and Maria to total around $225m.
Hiscox had previously estimated the same amount for Harvey and Irma alone.
The insurer, which underwrites a range of risks from oil refineries to kidnappings, also said claims arising from the Mexico earthquakes and California wildfires are not expected to be material for the group.
The third quarter of 2017 is expected to be the costliest on record for the insurance and reinsurance industry due to the run of natural catastrophes, with policy rates expected to go up as a result.
However Hiscox seems so far to be weathering the impact better than some rivals.
The underwriter reported gross written premiums for the first nine months rose 12.4% to £2.09 billion, helped by its Hiscox USA business.
As insurers report the full extent of the damage in their third-quarter results in coming weeks, investors will be looking for signs they can claw back some of those losses by raising premiums for customers.
A turnaround in prices would be the first major reversal since Hurricane Katrina in 2005, the costliest natural disaster in US history.
"The recent catastrophes are estimated to have cost the industry $100 billion and follow a decade of rate reductions. Therefore, it is not surprising that we are seeing signs of a hardening market," Hiscox said.
Hiscox said it was seeing price increases of between 10-50% for loss-affected and exposed US property lines, while rate reductions on London Market insurance lines are coming to an end.
It added that for its US catastrophe-exposed reinsurance business, it expects double-digit increases in rates during January renewals.
However insurance and reinsurance broker Jardine Lloyd Thompson (JLT.L) said today it did not expect the recent series of natural disasters to have an impact on its 2017 outturn.
It added that it was "premature" to draw conclusions on the insurance rating environment.