The last time South Florida trudged through this many hours of extreme heat, the world’s most popular search engine launched, John Glenn returned to space in the space shuttle Discovery and President Bill Clinton was embroiled in the Lewinsky scandal.
July 2023 marked one of the most persistent extreme heat waves in recent years, as South Florida endures one sweltering summer after another. And there’s no relief in sight for the seemingly endless excessive heat warnings.
Floridians will need to brace for more extreme temperatures and hazardous weather events in what Benjamin Kirtman, the director of University of Miami’s NOAA Cooperative Institute for Marine and Atmospheric Studies, calls “the new normal.”
“It’s truly out of bounds of anything we’ve seen in the entire instrument record,” Kirtman said of July’s heat wave, which struck Miami and the Everglades with alarming temperatures well above historical records. Kirtman called it “probably the biggest ratcheting up of climate change signals” he’s seen in his career.
Only seven months into the year, 2023 is currently third for the most hours spent with a heat index – or “feels-like” temperature – over 105 degrees, behind 1997 and 1998, according to Iowa State University heat index data collected at Fort Lauderdale-Hollywood International Airport.
On average, the city experiences around 55 hours with a heat index above 100 degrees in July alone. We’ve already hit 252 hours, nearly five times more than what is normally seen in an entire calendar year.
To meet Broward County’s criteria for a heat advisory, the feels-like temperature must reach a whopping 108 degrees for at least two hours. So far this year, Fort Lauderdale has spent four times the average number of hours – a total of 28 – above that threshold. At that level, 2023 comes in second only to 1998, a year that saw unprecedented heat across the state.
The record-breaking heat wave that seared Fort Lauderdale without respite in 1998 broke or matched nearly 1,500 daily maximum heat records from April to August.
Humidity is no joke in Florida, often rocketing the feels-like temperature many degrees above the raw air temperature. And with an ocean that’s warmer-than-ever, a dip at the beach might feel more like a soak in a hot tub.
The highest recorded real temperature captured at the airport last month was 95 degrees. Despite long hours under the heat, air temperatures would need to rise another five degrees to break records in Fort Lauderdale.
But as the days heat up, the relief of a cool evening at sunset is also becoming more rare.
In the latter half of the month, temperatures at sunrise were already hitting the 99-degree feels-like index. By sunset on July 23, the feels-like thermostat topped off at 118 degrees.
One of the biggest signals that South Florida’s climate is changing are nighttime temperatures, which are rising dramatically and have economic implications, according to Kirtman.
Experts warn that this can put extra strain on home energy usage, specifically an increased need for air conditioning as cooling degree days trend upward in Broward County. That strain, if left unsolved, could threaten how people manage to keep cool during future heat waves.
“A lot of people that live in Florida can’t afford to use air conditioning 24/7, so they’re counting on nighttime temperatures being cold enough to turn off their air conditioners,” Kirtman said. “The whole circadian rhythm of the human is dependent on being cool enough at night, so there are serious health implications associated with this.”