Global insured losses from disasters fell 33% to $20 billion in the first half of 2018, compared with $30 billion in the first half of 2017, according to preliminary estimates from the Swiss Re Institute, the organization said in a statement Thursday.

Global insured losses from natural catastrophes declined 28%, to $18 billion, from $25 billion the year before. Insured losses from man-made disasters dropped 60%, to $2 billion from $5 billion in the first half of 2017.

Most of the events leading to the insured losses “occurred in areas with high insurance penetration,” according to the report, resulting in some 56% of all global economic losses being insured.

Weather was the leading cause of losses in Europe and the U.S., the institute said.

The costliest event in the first half of 2018 was winter storm Friederike, which caused $2.1 billion in insured damages, the Institute said. Friederike caused substantial losses in Germany and the Netherlands, while France, Belgium and the UK were also hit. 

In the U.S., a series of winter storms including a nor'easter in March caused $2.9 billion in insured losses. The storms brought heavy snow, ice, freezing rain, and flooding from snowmelt and coastal flooding to large parts of the U.S., according to the institute.

The March nor’easter was the single largest loss-causing event for the insurance industry in the U.S. during the first half of 2018, leading to claims of $1.6 billion, the statement said.

Convective storms featuring thunderstorms, tornadoes and hailstorms caused insured losses of $1.1 billion in the U.S Southeast in March and another $1.1 billion in April in the U.S. and Canada, the institute said.

Insured losses have not yet been fully calculated from volcanic eruptions in Hawaii and Guatemala, and earthquakes in Japan, Taiwan and Papua New Guinea, the statement said.

The year is expected to see more extreme weather and insured losses, according to the institute.

"We expect to see more extreme weather conditions such as intense heatwaves and dry spells of the like we've seen over the last few weeks,” Martin Bertogg, head of catastrophe perils at Swiss Re Ltd., said in the statement.