Cloudy winter in South Florida ends as coolest in years with help of El Niño

Winter ended on Feb. 29 as the coolest in more than a decade for Palm Beach County as a formidable El Niño slathered South Florida in clouds and stabbed it with early season cold fronts that arrived as regular as the mail.

At Palm Beach International Airport, where the National Weather Service keeps an official gauge, the average temperature December through February was 68.3 degrees, which is near normal at 0.4 degrees warmer than the 30-year average.

But it was the coldest winter in West Palm Beach since the chilling days of 2010-2011 when temperatures averaged 65 degrees, iguanas died with frost on their backs, millions of dollars in crops were damaged and the mercury dropped into the 30s four times.

Meteorological winter runs December through February. Astronomical winter runs from the winter solstice on or around Dec. 21 through the spring equinox near March 20.

The cooler winter follows a year marked by oppressive heat and humidity as sea-surface temperatures spiked and cooling summer breezes faltered.

In West Palm Beach, 2023 was the second-warmest year on record in measurements that date to 1888. The summer months suffered from high dew point temperatures — a measure of the amount of water vapor in the air — with most weather-monitoring sites overseen by the Miami NWS having 30 to 50 days with at least two hours of heat index, or "feels-like" temperatures of 105 degrees or higher.

Lack of freezing temperatures near West Palm Beach this winter served to protect iguanas

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Mother Nature favored the invasive iguanas this past winter as no freezing temperatures were measured in South Florida, according to the Miami NWS office's seasonal report issued March 1. West Palm Beach’s coolest temperature was 47 degrees on Dec. 31. The temperature reached or exceeded 80 degrees on 20 days, which is below the average of 34 days.

“We absolutely noticed,” said Palm Beach property and landscape manager Carl May about the winter temperatures. “The cloudy days are wonderful for working outside because you are not dying from the heat, and it’s one of those things where just a few degrees can make a big difference.”

At Miami International Airport and Fort Lauderdale-Hollywood International Airport, this past winter’s temperatures were the coolest since 2014-2015 at 70.3 and 69.9 degrees, respectively.

The cooler temperatures, however, come with a climate change caveat, said Florida climatologist David Zierden.

In the past, El Niño typically meant winters marked by below-average temperatures. West Palm Beach has felt warmer-than-normal winters since 2010-2011, even during the strong El Niño event of 2015-2016.

“So, this year, with the background influenced by climate change, instead of cooler than normal, we are getting near-normal temperatures,” Zierden said. “Even with the increased cloudiness and rainfall impacting temperatures, they were just down to near normal.”

Statewide, the preliminary average temperature was 60.2 degrees, which is 1.3 degrees warmer than normal.

In the South Florida region overseen by the Miami NWS, only Naples had an average winter temperature below normal at 66.6 degrees, and that was just 0.4 degrees below the 30-year average.

Arctic air was trapped north of the polar jet stream

During El Niño years, the Pacific warms and trade winds weaken. That shifts the position of deep tropical thunderstorms in the Pacific, which disrupts upper air patterns. The jet stream gets shoved south over the Gulf of Mexico, where the rushing river of air incites storms in South Florida skies.

Robert Molleda, the warning coordination meteorologist with the Miami NWS, said the winter weather this season wasn’t as straightforward as some El Niño years.

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While the subtropical jet stream pushed to more southern latitudes, increasing cloudiness and mitigating daytime temperatures, the clouds also kept the air warmer at night. The low temperature of 47 degrees in West Palm Beach was the warmest winter minimum temperature since 1949-1950, according to the NWS report.

At the same time, the polar jet stream was weaker and farther north, trapping arctic air above it so that cold fronts that moved through Florida were warmer than if that frigid air had spilled deep into the subtropics.

“Even though we didn’t get the cold outbreaks of arctic air, we still had frontal passages that helped cool things down,” said NWS meteorologist Robert Garcia.

There were just six days in West Palm Beach with temperatures below 50 degrees. The 30-year average is 14 days.

Climate scientist Brian Bresschneider declared December and January the cloudiest winter on record for Florida based on data that goes back 80 years from the European Centre for Medium-Range Weather Forecasts.

While the clouds brought some areas of South Florida rainfall that made it into their top 10 wettest winters, including parts of Fort Lauderdale and Homestead, West Palm Beach got a near-normal amount of rain at 9.65 inches.

Clouds and rain were not a good mix for some foliage, said May, who battled fungus through the winter months.

“It was so murky,” May said. “If you are going to have cool weather, at least have some sunshine. In the garden, that makes a big difference.”

Kimberly Miller is a veteran journalist for The Palm Beach Post, part of the USA Today Network of Florida. She covers real estate and how growth affects South Florida's environment. Subscribe to The Dirt for a weekly real estate roundup. If you have news tips, please send them to kmiller@pbpost.com. Help support our local journalism: Subscribe today.

This article originally appeared on Palm Beach Post: National Weather Service: West Palm Beach winter was coolest in decade