It’s currently very hot in the Southwest. In parts of California, Nevada, Utah, and Texas, today’s predicted highs are well above 100 degrees. Those scorching three digit temperatures are expected to increase and persist across the region through the weekend, in the first heatwave of the season for some parts of the country.
The National Weather Service has issued excessive heat warnings for portions of western Arizona, southeast and central California, southern Nevada, and one county in Utah. In parts of California’s Central Valley, including Sacramento and Stockton, the worst of the heat is forecast to hit Friday, and the excessive warning expires after that.
In some areas like Phoenix, Arizona and its surrounding counties, the warnings extend from Thursday morning all the way through Sunday. Multiple counties in Nevada, including Clark County where Las Vegas is located, are also affected.
Excessive heat is defined as heat index values (the level of heat experienced considering both air temp and humidity) that climb higher than 105 degrees Fahrenheit for more than two consecutive hours. In Phoenix, the air temperature is expected to reach 114 degrees Fahrenheit on Saturday. East of San Diego, the forecast is 116 degrees. In Death Valley, the projected high is 120. Other swathes of the Southwest are under lesser heat advisories. All that heat is very likely to exacerbate the ongoing, Southwest megadrought.
After the Southwest, the heatwave is expected to move onto the Central U.S.
In total, more than 30 million people will be impacted by the extreme heat, according to reporting by the New York Times. High temperatures can cause heat related illness like heat stroke and exhaustion, but can also exacerbate existing health conditions like heart disease.
Heatwaves can be deadly for the most vulnerable like children, the elderly, disabled people, and those without access to cooling or shelter. Last summer’s heatwave in the Pacific Northwest killed over 100 people.
For places like Las Vegas, Salt Lake City, and Phoenix, this is the first heatwave of the year, adding additional risk. “Many people are not yet acclimatized to heat and may be impacted more than normal,” the NWS said in an advisory.
To minimize the danger, the NWS suggested people should wear light and loose clothing, avoid activity and work outdoors, spend time in air-conditioned spaces, and drink more water than normal.
But sweltering temperatures can threaten infrastructure like transportation and the power grid, which further compounds the safety risk by imperiling peoples’ ability to access those cooler spaces. That same, deadly PNW heatwave literally melted light rail cables, shutting down the streetcar—one of the city’s main forms of public transit. Earlier heatwaves this year in Texas led to warnings and pleas for people to reduce their electricity consumption, just when air conditioning was at its most necessary.
In an immediate sense, this heatwave is being brought on by a high atmospheric pressure system (called a “heat dome”) holding and trapping heat close to the ground. Bigger picture though: it’s probably climate change.
This heatwave is bringing potential record-setting highs, not necessarily because these temperatures have never been seen in these places before, but because of the timing. The 100+ degree temperatures are early. For instance, the Reno, Nevada area doesn’t usually reach highs above 100 until about a month later than this. The average annual first instance of 100 degrees there is July 6.
Scientists have been able to attribute multiple past heatwaves to human-caused climate change. The frequency of heatwaves across the U.S. has more than tripled since the 1960s. The total season in which heatwaves occur is almost 50 days longer. And individual heatwaves are now an average of a day longer, and more intense, according to the EPA.
Elsewhere in the world, extreme heat is becoming more intense and commonplace as well. Temperatures reached 122 degrees Fahrenheit across India earlier this spring. In May, Spain experienced one of its hottest weekends on record. Unless we collectively stop burning fossil fuels, things will only get worse.