The summer solstice is here. When can Dallas expect its first 100-degree day? (2024)

After heavy storms ravaged the Dallas-Fort Worth area at the end of May, and as scattered storms continue to roll by through the month of June, residents have already gotten a taste of extreme weather.

But as those storm clouds clear, they are going to uncover the sweltering Texas summer sun.

While North Texans seek refuge at public pools and splash pads, cooling centers, or in the air conditioning of their own home, a familiar question lingers: When are we going to have our first 100-degree day?

When will the temperature hit 100 degrees in summer 2024?

As with almost all other weather predictions, National Weather Service officials say it’s hard to give a definite answer.

“Even though we’re the meteorologists, we don’t really know any better than anyone else sometimes with these things, particularly when it’s something that could be weeks or months away,” said Daniel Huckaby, a meteorologist at the National Weather Service in Fort Worth.

According to the weather service, the average date of the first 100-degree day is July 1. This average is based on data dating back to 1899.

However, Huckaby estimated the excessive rain of this spring will likely push the first 100-degree day to after July 1 because wet ground and healthy vegetation usually reduce daytime temperatures.

Even so, it is still possible the first 100-degree day to occur sooner. A weather phenomenon known as ridging aloft — which is high pressure two to five miles above the ground — fuels excessive heat in the summer, Huckaby said. It typically occurs around the time of the June solstice — June 20 this year. If this occurs on schedule, he said, then it is possible for the first 100 degree day to occur in June.

How many 100-degree days will D-FW have?

On average, Dallas-Fort Worth hits triple digits 17 days per year.

This average is based on the same data set dating back to 1899, but data from more recent timeframes reflect an uptick in 100-degree days and warm temperatures.

Fifty years ago, D-FW had an average of 15 100-degree days per year, according to Huckaby. In the 30-year span between 1991 and 2020, there was an average of 20 days per year that reached 100 degrees.

In 2023, temperatures reached 100 degrees 55 times.

For summer 2024, the NWS has issued a warmer-than-normal outlook, as there has been a trend of warmer summers over the past few years, Huckaby said. Last year’s summer was the second hottest in Dallas’ history, and the third hottest for Dallas-Fort Worth.

These hot summers are in part due to climate change, but they are also due to positive feedback loops that reinforce warm temperatures, he said. Warm temperatures can strengthen some weather patterns — such as ridging aloft and droughts — that already cause warm weather, leading to even more warming.

“The weather that happens today is related to both yesterday and tomorrow,” Huckaby wrote in an email. “That correlation can be extended to longer time scales. If it were random like a game in Vegas, you’d expect that after several warm summers, a cooler one is bound to happen. But that’s not how climate works ... because it’s specifically not random.”

When has D-FW hit 100 degrees in the past?

While summers are getting hotter with more 100-degree days, the onset of these high temperatures seems to be delayed, Huckaby said.

One hundred years ago, the first 100 degree-day average varied from June 23 to 26. Huckaby said the lack of data played a role, but the past 50 years have been more steady. During this time, the average shifted from June 29 to July 1. The 30-year average from 1991-2020 places the first 100-degree even later at July 3.

“At first glance, I’m not sure why this is the opposite of what we’d expect, but it may have something to do with our trend toward wetter springs,” he said.

Are 100-degree days going to become more common?

John Nielsen-Gammon, a professor of atmospheric sciences at Texas A&M University, helped author a report that examined past and future weather trends in Texas from 1900 to 2036. The original report was published in 2021, but it has been updated in 2024 with additional data to refine the report’s predictions.

To examine 100-degree days, the report tracked trends across four regions of the state: coastal, northwest, northeast and south central. Over the past 50 years, the number of days over 100 degrees has just about tripled in three of four regions across Texas, the report says. The northeast region — which includes Dallas-Fort Worth — did not follow this trend, but that is because the region experienced heat earlier on, Nielsen-Gammon wrote in an email. The future trends in the northeast region are expected to be similar to the other regions of the state, he said.

According to the report, triple-digit days are going to be about four times as common by 2036 than they were in the 1970s and 1980s.

Urban areas are also expected to experience a greater frequency of 100-degree days due to the heat island effect, Nielsen-Gammon said. Urban areas are often hotter than surrounding rural areas because city infrastructure retains heat. Similarly, urban areas have less exposed soil and vegetation to cool down the surrounding air.

What should North Texans do in the heat?

Some of these steps to staying healthy in high heat include avoiding overexertion and drinking plenty of water, Nielsen-Gammon said. A greater concern arises for those who spend much of their day outdoors.

“It’s important for workers to be able to take extended breaks from the heat and have plenty of water available,” he said.

Nielsen-Gammon also noted challenges for those who do not have air conditioning. Cooling off at night allows the body to recover from the heat and can prevent major health problems. For those who do not have access to air conditioning, cooling centers can help people get through the heat and avoid heat-related health problems.