Rain, snow and early season freezing across much of the U.S. sent the country’s average temperature for October plunging to its coolest in a decade, after months of near record or record high temperatures.
But despite the national dip, it was the warmest October on record across the globe, and 2019 continues to trend warmer than normal in the U.S. and around the world.
The October average temperature across the lower 48 states was 52.3 degrees, about 1.8 degrees below normal, National Oceanic and Atmospheric Administration records show.
Record-setting cold and snow from the Pacific Coast to the Great Plains helped drop the national average temperature, despite much warmer than normal weather along the East Coast. Nine states experienced their top 10 warmest Octobers on record, including Florida, Georgia and the Carolinas.
In Oklahoma, the average temperature was 57.9 degrees, the 12th coolest October on record. The average high temperature was 70.5.
The snow and rain in many parts of the country also resulted in the nation’s eighth wettest October on record. Average precipitation for the lower 48 states was 3.14 inches, almost an inch above average.
Another new blast of cold air swept across the country Nov. 12-13, dipping as far south as Florida. More than 100 locations were expected to set or tie low temperature records.
Just because the U.S. experienced a cooler October and some icy temperatures this month, it should cast no doubts on the overall global warming trend, said Jonathan Gilligan, an associate professor of earth and environmental sciences at Vanderbilt University in Nashville, Tennessee.
Globally, average surface air temperatures were 1.24 degrees Fahrenheit above average for the period from 1981 to 2010, the European Union’s Copernicus Climate Change Service reported. That was just enough to edge out October 2015 as the warmest October on record.
Across the Southeast United States, average temperatures were more than 5 degrees above normal in October at more than half of the region’s 197 monitoring stations, said William Schmitz, a service climatologist and meteorologist with the Southeast Region Climate Center at the University of North Carolina, Chapel Hill. That heat continued the trend seen nationwide so far this year.
Across the nation, year-to-date temperatures as of Nov. 6 were warmer than normal at 634 of 896 monitoring stations. In at least 498 locations, the mean temperature was still at least 1 degree above normal.
Both Gilligan and Schmitz compared the difference in weather and climate to walking a dog on a leash. The weather is the dog, veering here and there, while climate is the leash, connected to the dog but maintaining a more consistent path — a path that is consistently warmer, Gilligan said.
“If you look overall across the world, the last five years have been the warmest years ever recorded for global temperatures,” he said. “This is expected to be the second or third hottest year on record.
“When you start looking at the averages overall, even the cold temperatures are mostly warmer than they were,” he added.
In Nashville, for example, it would drop below zero about once a winter between 1950 and 1979. The last time the mercury dropped that low in Nashville, said Gilligan, was Feb. 5, 1996.
An abrupt shift in weather patterns made October particularly interesting to climatologists like Bryan Peake with the Midwestern Regional Climate Center at the University of Illinois.
“The first part of the month we were dealing with record heat, with 800 or so daily records,” Peake said. “But the temperatures quickly shifted.”
Although the first fall freeze was slightly behind schedule, extreme cold arrived earlier than normal, followed by a stream of Arctic air that brought the early snowfall, he said. More than two dozen states broke daily and monthly snowfall records for October.
The National Weather Service has warned the nation could receive other abrupt shifts between intense cold and warm periods this winter.