The year 2015 was the second warmest and third wettest year in the United States since recordkeeping began 121 years ago, according to a new federal report released Thursday.
The annual report, put out by the National Oceanic and Atmospheric Administration (NOAA), found that along with extreme weather came more frequent and destructive natural disasters, including 10 extreme weather events in the U.S. in 2015 which racked up more than $1 billion in damage.
The worst month of the year was the last. In December, when floods and tornadoes battered large swaths of the South and Midwest, temperatures were the warmest ever for the month — 6 degrees above the average for the 20th century, the report found.
“This is the first time that a month has been both the wettest and the warmest month on record,” said Jake Crouch, an NOAA climate scientist.
Every state in the contiguous U.S. was warmer than average for the year, and four states — Florida, Montana, Oregon and Washington — had their warmest year ever.
Overall precipitation in 2015 was lower only than in 1973 and 1983, which like last year were both marked by an occurrence of the El Niño weather event, which is characterized by a warming of surface water in parts of the Pacific Ocean.
Scientists were careful not to tie the warmth and wetness of 2015 to any one factor. It was the 19th consecutive year of average temperatures rising higher than the average for the 20th century.
“We live in a warming world, and a warming world is bringing more big heat events and more big rain events to the United States,” said Deke Arndt, chief of the climate-monitoring branch of the NOAA. “2015 is emblematic of what we have already seen, and what we would expect in the future.”
Precipitation during the year hit some areas of the country harder than others. While Oklahoma and Texas had record amounts of rain, the West and Northeast had less rain than usual, and California had its 13th driest year on record. The Golden State would have had an even lower precipitation total if it had not received rain during the last weeks of the year.
Meanwhile, 10 extreme weather events struck the country in 2015, including tornadoes in the Dallas area during the last days of December and flooding along the Mississippi river about the same time. The Mississippi River often floods in spring, but it is rare to see such an event in winter.
“I think the fact that it was so warm in the East did contribute to the flooding,” Crouch said. “If it had been colder, a lot of that precipitation would have fallen as snow.”
The year was further distinguished by the wide variety of weather-related disasters, from drought to flooding to severe storms, massive wildfires and winter storms, NOAA scientists said.
“It is more common to observe three or four of these major disaster event types in a given year, as opposed to five or more disaster types that exceed $1 billion in the same year,” said Adam Smith, an applied climatologist at the NOAA.