Commercial insurance buyers will face rate increases next year after one of the most active and financially disruptive hurricane seasons, according to global broker Willis Towers Watson.

“Property rates for cat-exposed risks are going up, the multi-year streak of property rate reductions is probably over and insurers are going to be under pressure to raise rates in ways we haven’t seen for years,” Head of Broking for North America Joe Peiser said.

The extent of insured losses and impact on prices and capital levels remains uncertain, but the Willis Towers Watson Marketplace Realities report says property rates could rise 10-20% for catastrophe-exposed risks and 20-25% for risks with recent losses.

Other property cover buyers can expect flat rates or low single-digit increases amid a growing consensus that losses from recent catastrophes will top $US100 billion ($130 billion).

“Casualty rates, which had begun to drift downward for many organisations, are predicted to be flat or increase by small amounts as pressure from the recent catastrophe losses spills over into other lines of business,” the report says.

Factors that could dampen upward pressure include still-abundant capacity and “still eager” alternative capital providers.

Willis Towers Watson anticipates many specialty lines of business will follow their own supply and demand curves.

Cyber-insurance renewals average only single-digit rate rises despite a string of high-profile breaches, and experts forecast increases of up to 5% for next year.

Underwriters have offered premium reductions to organisations that can demonstrate increased security and internal policy controls.

For terrorism insurance, buyers should expect flat renewals, rather than the decreases they have seen recently, the report says.