For the eighth consecutive year, severe weather events caused damages exceeding $10 billion in the U.S., according to the latest estimates from the National Oceanic and Atmospheric Administration.
Each year, NOAA comprises data on the country's most economically damaging weather and climate disasters with costs that surpassed $1 billion.
"In 2015, there were five severe storm events with losses exceeding $1 billion each across the United States," NOAA National Climatic Data Center Applied Climatologist Adam Smith said.
Four of the five events occurred from April to June, which is the most active time of the year for U.S. severe storm activity, he added.
While the tornado season in the United States was calmer than normal during the typically active spring, the severe weather outbreak over Texas in late December was a significant contributor to the total losses in 2015.
"The fifth severe weather event of 2015 was the late-December [26-29] storm system, which produced the unseasonably strong tornadoes, widespread flooding and winter storm effects all of which were quite remarkable," Smith said. "To call this a historic event is not an overstatement."
"We saw anomalous warmth, instability and with it, anomalous humidity," AccuWeather Meteorologist Jim Andrews said, referring to the cause of the December event. "It is a big exception because it is not tornado season."
When including individual weather events, where damage was in the hundreds of millions of dollars, combined with these five, damages caused by severe storms exceeded $10 billion for the year.
While a severe storm or tornado may not be unheard of in the South in December, Andrews said the severity of the storms and the conditions that spawned the tornadoes are very rare.
This past year, there was a total of 10 different weather and climate disaster events with losses exceeding $1 billion each across the country.
These events included a drought event, two flooding events, five severe storm events, a wildfire event and a winter storm event. Overall, these occurrences, which include five distinct disaster event types, resulted in the deaths of 155 people and had significant economic effects on the areas impacted, Smith said.
It is more common to observe three to four distinct types of major disaster event types in a given year, he said, adding that five or more disaster event types exceeding $1 billion in the same year occur less frequently and include 2015, 2011, 2008, 1998, 1994 and 1989.
"Looking back over the last five years, 2011, 2012 and 2015 were extreme years climatologically, as we saw an impressive number and variety of all-time records broken," Smith said.
"During those years in particular, the U.S. experienced more extreme events, which is compounded by the fact that lots of our built infrastructure exists in hazardous areas."
For 2014, the Western drought topped the list as the most economically damaging disaster of the year and may be the number one on the list when the data is completed.
"We are planning to release the final 2015 event cost assessment this spring once all data is in final form," he said. "The impact of the Western drought is once again notable for the Western states."
The late-December storms had also provided a sizable contribution to the annual losses, but it was not yet clear to what extent.
"We are still assessing the total, direct costs, [which include insured and uninsured losses] resulting from the events of 2015," he said. "It will be several months before the costs from the late-December storms and flooding are more final."
At the moment, NOAA's website offers a variety of information and interactive elements including maps, tables, summaries and related hyperlinks.
NOAA has been collecting data since 1980, which analyzes the frequency and economic impacts of weather and climate disasters, in order to provide a better perspective on the occurrence of these type of events and help minimize risk in the future.
"We have adjusted for inflation for all events," Smith said, adding the increase in urban sprawl can also contribute to a rising loss of infrastructure.
The only data not currently available are the final 2015 event cost numbers, which may be finalized around March 2016, he added.