It Was the Warmest November—Ever
Average worldwide temperature in November was the warmest in 135 years of record keeping and the seventh consecutive month of record-setting high temperatures, the National Oceanic and Atmospheric Administration announced on Thursday.
With unusually warm weather expected through December, 2015 will likely end as the hottest year since record keeping began in 1880.
A wide expanse of warm water in the Pacific Ocean, part of the periodic El Niño weather cycle, contributed to the warm November conditions. Ocean temperatures worldwide were 1.5 degrees Fahrenheit above the 20th-century average for the month—another record—while land temperatures were 2.4 degrees Fahrenheit warmer than average, the fifth-highest on record for the month.
But if natural weather variations are the main players in the year’s weather, said Nick Bond, a climate scientist at the University of Washington, climate change is shifting the playing field. “With so much warmer-than-normal water, and the atmosphere interacting with the ocean, it’s easy to see that El Niño has helped make the whole planet warm,” he said. “But there is that slowly changing baseline of rising temperatures due to climate change.”
“There are some economic benefits—no one likes to spend a lot of money on heating oil, and Boston will probably be pretty happy if it doesn’t have to spend as much on snow removal this year,” Bond added. “But the trees need to go dormant, and the animals need to get those cues to hibernate. Just because you can play golf in December, doesn’t mean that this is a good thing.”
In the contiguous United States, temperatures from September through November averaged 56.8 degrees Fahrenheit and were the warmest in a 121-year record, NOAA said.
The autumn also saw above-average precipitation of 8.3 inches, the 15th-highest on record, which led to some improvement in drought conditions in the Mississippi Valley, the central and southern Plains states, and Alaska and Hawaii.
Extreme rainfall since early November in western Washington has helped ease the drought there but also caused major flooding and landslides. El Niño has been the major factor driving these storms, with some contributions from climate disruption. “There has been a slight increase in the tendency over the past few decades for heavy precipitation events in western Washington,” Bond said. “We have had, this past year, more days with 24-hour amounts of rainfall greater than an inch than we’ve ever had in the Seattle area.”
Snowpack levels are approaching or above average across much of the Pacific Northwest, a major improvement from one year ago. But Bond was cautious in his outlook. “In previous El Niño years we’ve seen a good start to the snowpack season, but in early winter it flattens off,” he said. “With the warm temperatures, we may end up again with less snow than usual."
Drought conditions continued across 19.6 percent of the nation as of mid-December, encompassing much of the region west of the Great Plains—including all of Nevada and California.