JACKSONVILLE, Fla. – It has been a warm summer in Jacksonville.
After a couple of heat waves with highs soaring into the upper 90s, the city has yet to hit 100° this year.
That’s because a lot of elements have to come together for the River City to enter triple digits.
The wind flow
One of the biggest factors for 100°+ temps in Jacksonville is the direction of the wind in the summer.
The region in the summer normally features a weak easterly flow. The flow creates a seabreeze in the early afternoon that pushes inland as the afternoon progresses.
It is nearly impossible for Jacksonville International Airport to get to triple digits during this onshore flow.
The seabreeze knocks down temperatures and stops the warmth from continuing in Jacksonville.
The opposite wind setup is a west or southwesterly flow. This is called an offshore flow.
In this instance, the seabreeze that does develop cannot move far inland due to the strong winds in the opposite direction.
With no seabreezes impacting the bulk of the city, temps continue to climb and could push into the 100° category.
Moisture around
Another factor is how moisture is in the atmosphere during warm spells.
Increased moisture creates showers and thunderstorms. This activity often develops in the afternoon hours.
The rain and storms end the building warmth and often send temperatures back down into the 70s and 80s.
No showers and storms in Jacksonville increases the chance of a 100° day.
But it doesn’t have to be just rain.
Cloud cover can also stop temps from moving into triple digits.
Rightly placed cloud cover over the city in the peak heating of the afternoon can hold temps in the mid and upper 90s.
A mostly sunny sky brings the chance of a 100° day even higher.
Upper-level ridge
A final ingredient for a 100°+ day is what’s going on in the upper levels of the atmosphere.
An upper-level ridge also needs to be present to push temps upward.
This ridge, sometimes called a heat dome, not only reduces coverage of rain and storms but also heats the mid and upper levels of the atmosphere.
Warmer temps in the atmosphere above Jacksonville further increase the chance of a 100°+ day in the city.
Will it happen this year?
Our best shot at getting to 100° so far this summer was this past Friday, July 21.
Many computer models indicated triple digits were likely, but the high in Jacksonville only climbed to 98°.
Another blast of heat is looking likely heading into early August.
While it is too early to know if 100° temps could develop, highs in the mid and upper 90s look likely.
The last time Jacksonville got to 100° was June 23, 2022.
It can get hot in Northeast Florida, but a lot of key ingredients have to come together just right to push Jacksonville into the triple digits -- no matter what it “feels like.”