By mid-morning, the town was sweltering. parked cars quickly became unbearable and the streets were largely devoid of people, except for a few construction workers drinking water and seeking shelter from the sun.
The air felt heavy and walking outside for more than a few minutes at a time was difficult, even for residents long-accustomed to the scorching temperatures of south Texas.
“Or they will come in and are asleep,” he added. “Exhausted to the point where they lose consciousness”.
Even with precautions in place, back-to-back days of scorching temperatures as high as 42C can end in tragedy. Despite the heat, hospital staff say, some workers continue to push themselves until it is too late.
“What really gets us is when we see patients come in with temperatures of 109F and are unresponsive. We have to do CPR. It’s just very sad,” Ms Valdez added. “These are young people”.
Globally, experts believe that July will likely be the hottest month on record. Here in Texas, the month saw several cities shatter heat records, with some parts of the state seeing sustained temperatures over 37 C for days on end.
Efforts to keep residents safe, however, are complicated by the fact that across the state, many workers are unable to avoid prolonged exposure to the sun and heat. In Dimmit County, for example, many workers are employed on farms, or in the oil and gas industry.
“It’s hot, but what’s to be done? If you don’t work, you don’t eat,” said Juan Gomez, an agricultural worker who lives near San Antonio. Even with ample water and rest breaks, he added, the heat “can really affect you if you don’t take care”.
Other workers are more dismissive of the dangers.
“It’s Texas…it’s hot,” said Everardo Ramirez, a construction worker. “I’m pretty used to it.”
How many residents take advantage of these programmes, however, is unclear. The BBC briefly visited two cooling centres in South Texas, only to find them largely empty.
In nearby San Antonio, many of the city’s main tourist sites, such as the River Walk, remain busy – even during the hottest hours of the day. Joggers breeze through public parks and outdoor workers – from construction workers to employees promoting restaurants – continue to ply their trade.
One construction worker in San Antonio, Alejandro Sanchez, told the BBC, “it’s hot, but I take care of myself”, while enjoying his afternoon lunch seated on a plastic chair in the blazing sun.
He was “not very worried”, he added, even as temperatures rose above 37 C.
BBC Ideas: Solving the air-con conundrum
Scorching heat strains US air conditioning capacity
This attitude stands in stark contrast to warnings from local officials, some of whom fear the worst is yet to come. Temperatures are expected to rise again this week as we head into August, historically the state’s hottest month.
“We’re going to have some challenges ahead of us,” said Roland Gutierrez, a state senator whose district covers a 35,000 square-mile swathe (90,600 sq km) of south Texas.
“Global warming is real, and we’re in the midst of it… people are dying.”
The letter stated that heat protection “is a matter of life and death for many workers and their families” across the US. It cited a number of specific incidents of workers dying in Texas due to the heat this year, including a 40-year-old postal worker who died in 46C heat.
Elias Diaz, a city councilman in the town of Eagle Pass, who also works at the county’s district hospital, told the BBC he feared profits would ultimately trump safety concerns at some work sites across the state.