Although most Texas temperatures will max out in the 90s, the humidity-driven heat index values will continue to surpass 100 degrees across the state.
National Blend of Models/Pivotal Weather
In the past few days, San Antonio weather saw brief but destructive storms Friday and the end of 100-degree heat on Saturday. Yet, in the next several days we’ll see more atmospheric stability as a system of high air pressure reasserts its influence on South Texas weather, according to the National Weather Service.
A subtropical ridge of high pressure over North Texas was expected to shift east on Monday, forecasters said. High atmospheric pressure in the summer typically produces a heat dome that can trap South Texas under a static weather pattern marked by above-normal temperatures and below-normal rainfall.
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“This will keep things hot, but not as hot as we’d seen in the two weeks leading up to Thursday and Friday’s rains,” the weather service said in a forecast bulletin for South Texas that was posted online Sunday. “Monday will be hot and dry with weak flow aloft and highs in the mid- to upper 90s to around 100.”
For San Antonio, Monday is shaping up to be partly sunny in the morning before gradually becoming sunny. While afternoon temperatures could climb to as high as 98 degrees, humidity will be limited, so the heat index will top out at only 102. Southeast winds of 5 to 10 mph, however, will continue to bring moisture-rich air into the region from the Gulf Coast.
At night, under mostly clear skies, temperatures overnight into Tuesday morning will stay above 76 degrees, forecasters said.
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Rain chances with Gulf disturbance
As a tropical low pressure system churned westward in the northern Gulf of Mexico, forecasters said they were anticipating slight chances for sea breeze showers and storms in the first half of the work week, especially for the Coastal Plains in Texas east of the Interstate 35 corridor.
“On Tuesday, an inverted trough (of low air pressure) will move inland from the Gulf, but it will be an open wave with very little upper-level support,” the weather service said. “The only areas that might see some rain Tuesday and Wednesday are the Coastal Plains as sea breeze showers and storms attempt to move further inland.
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In this weather satellite photo of the Gulf of Mexico taken Sunday morning, a tropical low pressure system produces a cluster of clouds off the Louisiana-Mississippi coasts that could bring rain chances to Texas in the coming days.
Geostationary Operational Environmental Satellites/CIRA and NOAA
Tuesday’s forecast and beyond
San Antonio on Tuesday should have plenty of sunshine as daytime temperatures once again peak at 98 degrees amid south winds of 5 mph, forecasters said. Wednesday is expected to be just as sunny and hot, with afternoon temperatures reaching 99 degrees.
Rain chances finally return to South Texas by Thursday, as San Antonio gets a slim shot at showers and storms (20% chance) after 1 p.m. Temperatures could max out at 99 degrees in the afternoon while bottoming out overnight around 77 degrees before sunrise Friday.
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The 20% rain chance is expected to persist Friday in San Antonio. Otherwise, look for more sunshine that day and temperatures hitting 99 degrees.
Should the high pressure loosen its grip on Texas, that could allow more rain-friendly weather systems to enter the picture, forecasters said.
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“Ridging (of high pressure) may finally begin to break down by next weekend, with a more active pattern possible as flow turns more
northerly,” the weather service said. “For now, we will remain optimistic about a pattern shift for the region.”