This story has been updated.

The National Weather Service has issued an excessive heat warning and heat advisory through Monday for South Central Texas, with temperatures expected to range from 105 to 108 and heat indexes reaching as high as 112 in some places.

“We have an upper-level ridge, which is like a dome sitting over us,” Mack Morris, a meteorologist with the National Weather Service told the San Antonio Report on Friday. “These are common in the summertime and this is what is responsible for this heatwave we’re experiencing.”

Heat index — or what the temperature feels like when relative humidity is combined with air temperature — matters because when humidity is higher, the body has a more difficult time cooling down, which can be dangerous.

Heat is by far the deadliest weather condition, according to the National Weather Service. Local officials are urging residents to take care to stay cool and safe, and to keep an eye on vulnerable populations like children, the elderly and pets.

City libraries and community centers are considered cooling centers, and will be open during regular business hours.

Those who must work outdoors should take frequent breaks and drink plenty of water.

Dozens of workers die and thousands more become ill while working in hot or humid conditions each year, according to the U.S. Department of Labor’s Occupational Safety and Health Administration. OSHA requirements make sure that area employers protect outdoor workers from heat illness by allowing ample shade, water and rest.

Much of South Texas is in the throes of what is becoming the region’s hottest summer on record. May and June this year were San Antonio’s hottest on record, according to reports by the National Weather Service. Along with the heat, the region is in extreme drought, which has also increased wildfire risks and affected aquifer levels. 

Why is it so dang hot? There are three main reasons, State Climatologist John Nielsen-Gammon told the San Antonio Report last month: low moisture in the soil, weather patterns bringing in dry air from urban Mexico and climate change.

While summer heat waves are typical in Texas, climate change is influencing their severity, he said. As weather conditions become more severe due to climate change, drier and longer droughts are likely to become more prevalent.

To add insult to injury, most residents are also now dealing with higher CPS Energy bills. One big reason is that air conditioning, which can make up fully half of a residential electric bill, simply can’t keep up beyond about a 20-degree differential with the outside temperature. Many systems will run almost constantly in attempt to do so, however, and that drives up costs.

Setting a home’s thermostat higher can help, but if it’s 103 outside, even setting it to 78 or 80 means the air conditioner will struggle to keep up, and use more energy to do so.

Friday was a Yellow Day for CPS Energy customers, part of the color-coded conservation level program the utility rolled out last month. Yellow days mean customers should conserve power between 2 p.m. and 7 p.m., when demand is highest.

With rivers around South Central Texas drying up, some residents may find relief at San Antonio’s city pools.

According to the parks and recreation department, 21 outdoor pools are now open — and don’t forget the city’s six splash pads.

Genevieve Adame and Lindsey Carnett contributed to this report.

Avatar photo

Tracy Idell Hamilton

Tracy Idell Hamilton covers business, labor and the economy for the San Antonio Report.