July 2025 will go down in the record books as the hottest July ever recorded in Jacksonville.
At Jacksonville International Airport, the city’s official climate site, the thermometer hit 98 degrees or higher on more than nine days, a scorching feat that helped crown this July as the hottest on record in terms of average temperature.
JAX ranked the fourth hottest July based solely on afternoon daily maximum temperatures. The string of record-setting highs that closed out the month from July 26 through July 29, either tied or broke daily records, pushing the heat into rare territory.
So, what triggered the late-month heat wave? A stubborn ridge of high pressure parked over the southeastern U.S. created a dome of sinking air pumped by full sun heating day after day and reduced the night cool downs.
But here’s where the science sizzles. When factoring in the overnight lows — which stayed stubbornly warm thanks to elevated humidity and urban heat retention — the combined average of highs and lows made this July the hottest ever recorded, not just in Jacksonville but in Gainesville as well.
Several other cities in Florida and the Southeast broke long-held heat records.