It’s not just you: This winter was warmer and wetter than normal in Nashville.
Experts say those higher temperatures are part of a warming trend in the Nashville climate over the past few decades, even accounting for normal fluctuations in weather.
The big picture: Temperatures, rainfall and snowfall levels fluctuate from year to year. But a zoomed-out view of weather data can show slow shifts in climate, revealing things are warmer than they used to be in Nashville.
The hottest Nashville February on record was in 1882, when average daily temperatures reached 51.4 degrees Fahrenheit. This February did not top that record, but it came close, with average temperatures reaching 48.9 degrees.
The National Weather Service also clocked February 2019 as the rainiest February on record.
Above average since 2016
Although not record-breaking, February 2019 temperatures were overall above average.
Records collected by the NWS since 1875 show average February daily temperatures sit around 41.6 degrees—more than 7 degrees below this year’s reported temps.
December 2018 and January 2019 were also warmer than average.
On the flip side, historic records show that low temperatures in Nashville have often dropped below zero—far under the depths Nashville reached in this past winter.
“Winters have gotten so warm in the last 20 or so years that people forget. Weather that wouldn’t have been remarkably cold 30 or 40 years ago seems extraordinarily cold today,” said Jonathan Gilligan, associate professor of earth and environmental sciences at Vanderbilt University.
Historic records show Nashville used to see below-zero cold spells, on average, once a winter before 1980, he said.
The last time the mercury in Nashville dropped below zero was more than 20 years ago, according to Gilligan.
“It feels a lot colder to people than it would have if they had that historical perspective,” he said.
First day of Spring: Above-normal temps, rainfall to follow
A handful of individual days this winter did see record-high temperatures: Jan. 8, Feb. 5 and Feb. 7 each beat records as they hit highs in the 70s.
Looking ahead to spring, NWS prediction maps show Tennessee and much of the Southeast are likely to have above-normal temperatures and precipitation levels between March and May.
Spring officially begins March 20 with the vernal equinox at 4:58 p.m., the precise moment the sun’s rays shine directly on the equator. It’s one of two days out of the year—the other being the autumnal equinox in September.
Some of that warmth and precipitation may be a side effect of a brewing El Niño system in the Pacific. El Niño patterns occur when Pacific Ocean currents off the coast of Peru and Ecuador warm up.
The warming ocean currents can trigger dramatic weather changes in the region and a major El Niño event can bring changes to weather patterns worldwide, according to NWS.
El Niño generally forms every three to seven years, according to the service.
There have been at least five El Niño events recorded since 2000, but the last major one spanned 2015 to 2016. Weather in Nashville in both of those summers can be summed up in two words: Hot and wet.
In both 2015 and 2016, average daily temperatures for June, July and August surpassed historic averages.
Rainfall totals for those same months were nearly 3 inches above average in 2015 and more than 6 inches above average in 2016.
How has warmer weather affected Nashville’s ecosystem?
In some ways, warmer winters can be helpful. Pipes rarely freeze, it takes less energy to heat homes, road conditions are more favorable, and so on. But in many other ways, the lack of truly cold weather is changing Nashville and Middle Tennessee.
Fruit trees, for example, need to get properly cold in the winter to bear healthy fruit in the summer, Gilligan said.
Peach varieties can vary as to how much chill they need, but Gilligan said the harvest does best in years that see approximately 800 hours below 45 degrees between Oct. 1 and Feb. 15, a number that researchers have said used to be normal in Georgia.
Farmers there saw devastatingly low peach harvests after the winter of 2016–2017, he said, because that winter only about 500 hours clocked in below 45 degrees
“We’re seeing longer warm periods, and that seasonality we’re historically used to in Middle Tennessee is shifting. It’s expanding into more months,” said Janey Camp, research associate professor in civil and environmental engineering at Vanderbilt.
That means, experts say, that the roster of both ornamental and agricultural plants that thrive in Middle Tennessee and the Southeast may be changing from what previous generations knew.
“We can still be listening to and paying attention to it, but not all of the wisdom from grandparents and previous generations can still apply,” Vanderbilt’s greenhouse manager Jonathan Ertelt said.
Ertelt has worked with plants in Nashville since the late 1970s, when he moved to the area to work in the botanical gardens project at the Cheekwood Estate and Gardens.
“We have to listen with the awareness that we’re dealing with a changing system now,” Ertelt said. “I’m tickled I can grow as many palms in my front yard as I can now, but I’m not sure the cost we’re paying in order for me to be able to do these things is worth it.”