Every single state and every single city in the Lower 48 states was warmer than normal in 2016. For the nation, the year ranked second-warmest in records that date back to 1895.
The nation's average temperature was 54.9 degrees, nearly 3 degrees above the long-term average, NOAA reported.
Only 2012 was warmer in historical records, NOAA said, by less than half a degree.
The U.S. has had 20 straight warmer-than-normal years and is warming at the rate of 0.15 degrees per decade.
All of the Lower 48 states registered one of their top-seven warmest years. "The breadth of the 2016 warmth is unparalleled in the nation's climate history," NOAA said. "No other year had as many states breaking or close to breaking their warmest annual-average temperature."
Thirty-four cities recorded their warmest year, from the Gulf Coast to the shores of the Arctic Ocean, and include: Asheville, New Orleans, Houston, Atlanta, Nashville, New York (La Guardia), Harrisburg, El Paso, Juneau and Barrow (Alaska).
Alaska posted its warmest year on record for the third time in as many years. Its temperature was nearly 6 degrees above average and is rising at the feverish pace 0.3 degrees per decade.
Set against the backdrop of record- and near-record warmth, the nation witnessed extreme rainstorm after extreme rainstorm.
Based on an analysis from reinsurer Munich Re, USA Today reported last week that the U.S. experienced 19 floods in 2016, more than any other year on record.
Several extreme rainfall events were described as 1-in-1,000-year occurrences, including torrents that swamped northern Louisiana in March, Greenbrier County, W.Va., in June, Ellicott City, Md., in July, southern Louisiana in August and eastern North Carolina in October (from Hurricane Matthew).
NOAA reported that 2016 produced 15 weather- and climate-related disasters exceeding $1 billion in damages, second most on record — behind 2011's 16.
"Perhaps most surprising were the four separate billion-dollar inland flood (i.e., nontropical) events during 2016, doubling the previous record, as no more than $2 billion inland flood events have occurred in a year since 1980," NOAA said.
A NOAA index that tracks extremes in climate found 2016's levels in the U.S. were 121 percent above average, second-highest on record. Unusually frequent hot days and nights elevated this index to near-record levels.
The abnormally warm temperatures in 2016 were not unique to the United States. Next week, NOAA and NASA are expected to announce that 2016 was the warmest year on record globally for the third time in as many years.