Shown is a forecast temperature map from the first strong cold front of fall 2025, which pushed through San Antonio on the night of Oct. 28. The average date for San Antonio’s first cold front typically comes a couple weeks earlier in the year.
WeatherBell
September has arrived, but it’s still really hot across South Texas. Afternoon temperatures in San Antonio reached the upper 90s on Tuesday, and they are expected to climb close to 100 degrees through the rest of the week, while humidity-driven heat index values could approach 105 degrees or higher.
Despite the summer-like heat, Tuesday marked the first day of meteorological fall. That’s different from the traditional start of fall, which doesn’t arrive until the autumnal equinox on Sept. 22.
Article continues below this ad
So why do meteorologists use a different start to the seasons? First, the traditional start to the seasons vary slightly from year to year, which can mean inconsistent data comparisons. To make things simpler, meteorologists instead use fixed dates: fall begins Sept. 1, winter Dec. 1, spring March 1 and summer June 1.
Secondly, meteorological seasons more closely align the earth’s natural temperature patterns. During fall, average temperatures start to cool down more noticeably as the polar jet stream in the arctic starts to move south toward the United States. As that shift occurs, cold fronts gradually become more frequent across Texas.
This NOAA diagram shows the positions of the subtropical and polar jet streams. During the summer, the polar jet stream shifts to the north, closer to the North Pole. During the fall, it starts to to move back south.
NOAA
During September, however, most cold fronts that reach Texas are relatively weak, dropping temperatures by only a few degrees at a time. So if you’re looking forward to some truly cooler weather, when does San Antonio typically see its first strong cold front of the fall?
Article continues below this ad
For that, we have to look back at weather history.
Typical first strong cold front
To determine when San Antonio typically gets its first strong cold front, we analyzed temperature data from every year since 2000, pinpointing the date when the first strong front arrived each year. To be considered strong, high temperatures had to fall by at least 15 degrees from one day to the next.
After finding each front and averaging those dates together, it was found that San Antonio’s first strong cold front typically arrives in mid-October — Oct. 14 to be exact. This lines up closely to the average first day when low temps fall to 50 degrees or colder, which occurs Oct. 16.
Article continues below this ad
Of course, Oct. 14 is just an average. The actual first strong cold front can arrive significantly earlier or later depending on the year. For example, last year’s first strong cold front came on Oct. 28-29, when high temperatures plunged from the 90s into the 60s in just 24 hours.
Looking even farther ahead, San Antonio’s average first day with low temperatures in the 30s is Nov. 13, while the city’s typical first freeze occurs during the first week of December.
2026 fall outlook
According to the National Weather Service’s fall outlook, South-Central Texas is slightly favored to experience above-average temperatures during meteorological fall. That’s largely because September is expected to be significantly warmer than average, with summer-like weather likely to persist through much of the month.
Article continues below this ad
Shown is the National Weather Service’s fall outlook, which shows that Texas is slightly favored to see above-average temperatures during meteorological fall.
Climate Prediction Center
By late October and November, El Niño is expected to play a larger role in the weather across the region, potentially bringing below-average temps into the region. El Niño, the warming of the equatorial waters in the eastern Pacific, typically shifts the Pacific jet steam closer to Texas, resulting in more frequent cold fronts and a more active storm track across the southern United States.
The effects of El Niño are likely to become even more pronounced during the winter. In San Antonio, El Niño winters are an average of 1.4 degrees colder than non-El Niño winters and bring an average of 58% more precipitation.