The year 2010 tied with 2005 as the planet's warmest on record, and 2010 was also the wettest year, according to the National Oceanic and Atmospheric Administration.
Nine of the past 10 years also rank among the 10 warmest on record, reinforcing the idea that the planet is heating up, the warming driven by emission of carbon dioxide and other greenhouse gases.
The warming trend was apparent in surface-temperature data despite two unusually cold winters in a row in the eastern United States, said David Easterling, chief of the scientific services division at NOAA's National Climatic Data Center in Asheville, N.C.
"Does this disprove climate change, climate warming?" Easterling said in a telephone press conference Wednesday. "The answer is, unequivocally, 'No.'"
The climate agency's year-end summary totals up surface temperature, rainfall and other data for the year, then compares them with global records going back to 1880.
The year 2010 was the 34th consecutive year with global temperatures above the 20th century average, the summary says, with combined land and sea-surface temperatures 1.12 degrees Fahrenheit above the average.
But while the average temperature in the contiguous United States alone was above average, this was only its 23rd warmest year on record.
The year was notable for a number of "extreme events," Easterling said, including "the Russian heat wave, and, related to that, flooding and heavy rains in Pakistan; also record warm temperatures in the summer."
High precipitation levels included record rainfall in Southern California. From Jan. 1 to Dec. 31 2010, John Wayne Airport saw 22.57 inches of rain, nearly 7 inches above normal.
The rains came despite a transition to La Niña conditions later in the year, a periodic cooling of the eastern Pacific that typically means a dry rainy season for Southern California.
In fact, because La Niña tends to lower global temperatures, 2010 might have been even hotter without it.
"December was actually not nearly as warm as the months in the middle of the year," said Deke Arndt, climate monitoring branch chief at the Climatic Data Center. "So we did see that La Niña signal kick in towards the end of the year."
Wet weather dampened the risk of wildfire, as well as drought for the nation as a whole. In July, the drought footprint covered less than eight percent of the country.