FORT LAUDERDALE, Fla. — Another unusually warm winter is in the books for South Florida, the second-warmest ever recorded in Miami and Fort Lauderdale.
“It may sound like a broken record, but South Florida experienced yet another warmer than normal winter,” meteorologists with the National Weather Service Miami wrote in their summary of the winter season Friday.
This year’s winter was characterized by extremes: long stretches of hot days, and a few intense cold fronts that plunged temperatures as low as the 30s. It was also a rare third consecutive La Nina year, the first such event of the 21st century.
Although much of South Florida’s weather correlates with what scientists expect from the phenomenon, it’s difficult to say whether climate change may also have played a role in this winter’s lingering, dry heat.
Here are some of the takeaways:
—Average winter temperatures mostly stayed 3 to 4 degrees above normal.
—Meteorologists recorded above normal temperatures on more than 80% of days throughout the South Florida region.
—This was the second-warmest winter ever recorded in Miami and Fort Lauderdale, after the winter of 2016-17.
—Miami International Airport recorded temperatures at or above 80 degrees for 72 days of the season, the highest number recorded since 1895, and nearly twice the average of 43 days.
—Fort Lauderdale/Hollywood International Airport recorded temperatures at or above 80 degrees for 61 days of the season, nearly twice the average of 35 days.
—Much of southern Florida experienced a drier than usual winter, though thanks to a few days of rain, Broward and Miami-Dade counties reached slightly above normal levels of precipitation. Areas to the north and west, however, saw lower than usual rainfall.
—Only two cold episodes came this year. The first was the Christmas cold snap, from Dec. 24-26, when temperatures stayed below 60 degrees for three consecutive days. A second snap came January 14-16, when temperatures plummeted into the 30s.
This winter’s unusual warmth arose out of a particular weather pattern that shielded Florida from the cold, a “hallmark” of La Nina winters, the report says.
Stronger than normal mid- to upper-level high pressure hung over eastern North America, the Gulf of Mexico, and the western Atlantic Ocean.
The pressure acted like a “block,” said Luke Culver, a meteorologist for the National Weather Service Miami, stopping cold fronts before they could reach South Florida. This is pretty standard, he added, but “the length of time that it was persistent over us is what made it a little more unusual.”
Alongside the pressure, a jet stream, a band of wind that follows the boundaries between cold and hot air, positioned itself over the Central and Mid-Atlantic U.S. La Nina causes the jet stream to move north and weaken over the U.S., with warmer and drier conditions in the South, and colder and wetter winters in the North.
This winter marked the third consecutive winter of an “unusually stubborn and protracted” La Nina, a Wednesday news release from the World Meteorological Organization said.
While two consecutive La Ninas are fairly commonplace, a “triple dip” is rare. This winter was the first of the 21st century to see one, the third since 1950, according to the WMO.
It’s possible that climate change also played a role in this year’s unusual warmth, but it’s hard to say in the short term.
Climate change is correlated with warmer and drier weather in the long run, Culver said, but it’s difficult to pinpoint its role in specific instances like this past winter.
“It’s possible, but you can’t say what was driving that,” he said. “Especially because that’s such a long-term scale.”
Researchers also believe that greenhouse gas emissions may lead to stronger and more frequent La Nina and El Nino events like this year’s triple-dip.
“Extreme El Nino and La Nina events may increase in frequency from about one every 20 years to one every 10 years by the end of the 21st century under aggressive greenhouse gas emission scenarios,” said Michael McPhaden, a Senior Scientist at the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory, in a 2020 press release.
A study published at the University of Washington found that climate change may be partially responsible for increasing La Nina conditions in the short term, though El Nino conditions may take over in the long term.
“Our work raises the possibility that the recent trends toward more La-Nina-like conditions may be partly a response to anthropogenic forcing,” researchers wrote, “even though most existing climate model and paleoclimate evidence suggests that trends will eventually reverse toward more El-Nino-like conditions.”
Forecasters predict a warm, dry — and perhaps even scorching — spring.
“Springtime is generally our driest time of year to begin with,” Culver said. South Floridians are heading into the driest time of year with drier than normal weather and increased chances of thunder and lightning that can spark wildfires.
Close to 90% of Florida is “abnormally dry,” according to NOAA’s National Integrated Drought Information System. The drought conditions will likely worsen in the coming weeks, putting the risk of wildfires “above normal” for the entire South Florida region.
“The significant wildland fire potential is above normal through May for all of South Florida,” the report read. “All persons are urged to take measures to reduce the chance of wildfires.”
Wildfire chances will continue to increase as May approaches and temperatures warm even further.
Southwest Florida is particularly at risk, Culver said. Already, fires have begun to pop up in Charlotte and Collier counties. On Friday, a wildfire in Collier County forced evacuations.
Despite its lingering effects, La Nina will subside into “neutral conditions” in the coming months, Culver said. An El Nino event may follow, though it likely wouldn’t be until the end of summer or fall.
If it comes, South Floridians might find some relief, within reason. The phenomenon has a suppressing effect in the Atlantic, which could mean fewer hurricanes, Culver said, “but that doesn’t necessarily mean there won’t be anything.”