Two separate reports, one from Aon and the other from NOAA’s National Climatic Data Center (NCDC) highlight the impact of billion-dollar weather events.

In its latest global catastrophe recap, Aon reports that several multi-day severe weather outbreaks caused significant damage across much of the eastern and central United States during May, both causing billions of dollars in damage.

The most notable stretch was highlighted by an EF-5 tornado that caused catastrophic damage in Moore, Oklahoma. The tornado left 24 people dead, 387 injured and damaged/destroyed up to 13,000 homes and structures. At least 61 tornadoes touched down during the event.

Total economic losses were expected to approach or exceed $5.0 billion, with insured losses of $2.5 billion or more anticipated, according to Aon.

Another period of severe weather prompted multiple tornado touchdowns in the greater Oklahoma City, Oklahoma and St. Louis, Missouri metropolitan regions.

Aon reports that at least 76 tornadoes touched down during the event, including an EF-5 with 295 mph (475 kph) winds and a record 2.6-mile width (4.2-kilometer) in El Reno, Oklahoma.

The event was also notable for a major hailstorm in Amarillo, Texas (that caused insured losses alone of $400 million), flash floods in the Plains and Midwest, and damaging winds in the Northeast. Aon reports that total economic losses are expected to be beyond $2.0 billion, with insured losses in excess of $1.0 billion.

Meanwhile, NOAA’s NCDC reports that 2012 saw 11 weather and climate disaster events each with losses exceeding $1 billion in overall damages across the U.S.

The 2012 billion-dollar events included seven severe weather/tornado events, two tropical storm/hurricane events, and the year-long drought and associated wildfires.

These events caused over $110 billion in overall damages throughout the year, making 2012 the second costliest year on record. (2005 was the most costly year on record since 1980 with $160 billion (in 2005 dollars) due to four land-falling hurricanes, including Katrina.

NCDC reports that the two major drivers of damage costs in 2012 were Sandy, at approximately $65 billion in overall damages and the year-long drought at about $30 billion.

It should be noted that NCDC estimates incorporate both insured and uninsured losses and estimates from other federal agencies, state governments, insurers, and other sources.

With 11 events, 2012 also had the second highest number of billion-dollar disaster events behind 2011 which had 14 events, NCDC adds.

Check out I.I.I. facts and statistics on U.S. catastrophes.