Texas—Texas is not ready to let go of summer just yet. From Dallas-Fort Worth to South Texas and the Gulf Coast, residents have spent much of the season dealing with repeated stretches of temperatures near or above 100 degrees, and some communities have also faced dangerous heat indexes.
Even with September underway, the heat story is far from finished. While another triple-digit day is certainly possible in parts of the state, historical weather records suggest that 100-degree temperatures generally become less frequent and shorter-lived as September progresses.
That may offer some relief to Texans wondering when they can finally put the hottest part of summer behind them. But the timing is different depending on where you live.
September Does Not Always Mean the Heat Is Over
For Texans hoping that the arrival of September automatically brings cooler weather, the calendar can be misleading.
September is still capable of producing intense heat, particularly in the southern half of the state. Temperatures do not suddenly drop when August ends. Instead, the transition toward fall typically happens gradually, with more meaningful cold fronts becoming common later in the season.
This year, that transition could take some time.
The Climate Prediction Center has favored above-normal temperatures across much of the western and central United States for September through November. That does not mean Texas will remain locked in triple-digit heat throughout the fall. Rather, it suggests temperatures may run warmer than the historical average more frequently.
So while the worst of summer may be winding down, Texans should not assume every remaining September day will feel like fall.
Why Has Texas Been So Hot?
One major factor behind the persistent heat has been a recurring high-pressure pattern, sometimes described as a heat dome.
High pressure can suppress clouds and rainfall, allowing more sunlight to reach the ground and temperatures to climb. The sinking air associated with high pressure also warms as it descends.
When that pattern sticks around for days or even weeks, the heat can build.
The problem can become even more noticeable when overnight temperatures stay unusually warm. Instead of allowing homes, buildings and infrastructure to cool significantly after sunset, elevated nighttime temperatures keep the heat locked in.
Broader atmospheric conditions have also favored above-normal temperatures across portions of the southern and central United States.
Meanwhile, the Climate Prediction Center said in August that El Niño was strengthening, with a greater-than-90% chance of a very strong event during the fall and winter.
Interestingly, El Niño does not have a simple relationship with Texas summer heat. Its more recognizable influence in the state often arrives later in the year, when it can contribute to cooler and wetter conditions during late fall and winter.
When Does Texas Usually See Its Final 100-Degree Day?
Historical records show that the answer depends heavily on location.
According to National Weather Service data covering records since 1940, the average last 100-degree day occurs as early as August in many Texas cities, although some locations have historically experienced triple-digit temperatures well into September or even October.
In Austin, the average final 100-degree day is August 24, while the record extremes range from June 13 to October 13.
Dallas-Fort Worth typically sees its last 100-degree day around August 29, while San Antonio’s average is August 26.
Farther west, El Paso’s average final 100-degree day arrives around August 11, while Lubbock averages August 2. Amarillo’s average is even earlier, at August 5.
South Texas can stay hot longer. Corpus Christi has an average last 100-degree day of August 29, but its latest occurred on October 17, 2012.
Other notable records include Waco’s latest 100-degree day on October 15, 2024, Midland-Odessa’s on October 8, 1979, and San Antonio’s on October 4, 2023.
Those records make one thing clear: September heat is not unusual in Texas, and October triple-digit temperatures, while rare, are not impossible.
When Can Texans Finally Expect Cooler Weather?
For most of Texas, October is when the transition toward consistently cooler weather becomes much more noticeable.
That does not guarantee an immediate end to hot days. A warm spell can still develop, and isolated 100-degree readings can occur unusually late in the year.
But historically, triple-digit temperatures become increasingly unusual as fall progresses.
For Texans watching the thermometer and waiting for relief, the message is simple: the heat is likely entering its final stretch, but summer is not necessarily finished yet.
Where you live in Texas matters, and South Texas may have to wait longer than northern or western parts of the state.
For now, residents should continue keeping an eye on local forecasts, especially during periods of extreme heat. And if history is any guide, the odds of repeated triple-digit stretches should continue to decline as September gives way to October.
When do you usually consider Texas summer officially over? Share your thoughts and tell us how hot it has been where you live.