The sun shines bright over The Alamo on Tuesday, Aug. 18. San Antonio temperatures have topped out at 100 degree or higher in five of the past seven days, and triple-digit heat shows no signs of stopping.
San Antonio Express-News/Anthony Franze
During the first half of summer, temperatures across South Texas were below-average, largely due to high rainfall across the region. San Antonio’s average high temperature during June and July was just 92.6 degrees, and the city only saw one day with a high temp of at least 100 degrees.
However, more typical summer weather has finally moved into South Texas during August, especially over the past week and a half. Since Aug. 10, San Antonio temperatures have risen to at least 98 degrees each day, and highs have topped out at 100 degrees or higher five times.
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Intense heat with several more 100-degree days is expected over the next few days. But exactly how long will highs stay in the triple digits? Here’s a look at the upcoming forecast and what long-range weather models are saying.
Wednesday’s forecast
A mild morning is anticipated across South Texas on Wednesday, as temperatures will sit in the upper 70s to near 80 degrees through 9 a.m. Partly cloudy skies are also expected early on, with skies expected to become mostly sunny by the mid- to late morning.
Temperatures will rise fast, likely reaching the 90-degree mark just after 11 a.m. Then by 4 p.m, afternoon high temps are likely to reach 100 to 101 degrees. There will be a bit more cloud-cover than there was on Tuesday, but mostly sunny skies will prevail.
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Shown are the expected high temperatures across South Texas on Wednesday
Pivotal Weather
Of note, humidity levels will be lower than we’ve grown accustomed to this month. With dew points expected to fall into the low to mid-60s, heat index values will be just a couple degrees hotter than the actual temperature, topping out near 103 degrees. Winds will stay very light, moving in at 5 to 10 mph.
San Antonio will be very slow to cool down during the evening. By 8 p.m., temperatures are still likely to be around 97 degrees, and the city won’t drop under 90 degrees until around 10 p.m.
High heat continues
Weather models are showing that temperatures will stay relatively consistent over the next few days, possibly even rising by another degree or so. On Thursday, San Antonio will likely reach 101 degrees again, potentially rising to around 102 degrees by Friday. Increasing humidity will also force heat index values to rise, reaching up to 109 degrees.
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Triple-digit heat will stay in the forecast on Saturday, and a few heat-induced thunderstorms may also develop. However, rain chances in San Antonio are only expected to be near 10% to 20%. High heat will stick around Sunday too, with temperatures at 101 to 103 degrees.
How long will 100-degree heat stick around?
With high pressure continuing to hover over Texas next week, temperatures are likely to stay in the triple digits at least through Wednesday, Aug. 27. While still uncertain, weather models do show that high pressure may weaken by the second half of next week, which could bring temperatures back down into the upper 90s.
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That said, if high pressure stays centrally located over Texas, daily triple-digit temperatures could last through Aug. 30. Gradual cooling is finally expected to occur over the region as the calendar flips to September. But until then, the high heat is here to stay.