California braces for another heat wave as climate change and drought take their toll

The National Weather Service issued an excessive heat warning Tuesday for much of California that will last from Wednesday through next Monday, the third potentially record-breaking heat wave over the last two months in a state racked by a drought made worse by climate change.

Temperatures are forecast to reach 116 degrees in the valleys of San Diego over the weekend, and even higher in desert portions of the state. In the Central Valley, where much of the nation's food is grown, temperatures are forecast to reach 111 degrees on Sunday, and Yosemite National Park could see temperatures of over 108 degrees for several days in a row, the National Weather Service warned.

Virtually the entire state of California is experiencing extreme or exceptional drought, according to the U.S. Drought Monitor, and higher temperatures bring an elevated risk of wildfires. After a heat dome covered much of the Pacific Northwest and British Columbia last week, two wildfires erupted in Northern California. Water levels at reservoirs and lakes in the state continue to drop, and the snowpack has all but vanished.

"The drought is leading to extremely low soil moisture, which is making it easier for these high pressure systems to generate extreme heat waves because more of the sun's energy is going into heating the atmosphere rather than evaporating nonexistent water in the soil," Daniel Swain, a climate scientist at UCLA, told NPR, adding, "That's sort of the vicious cycle of drought and extreme heat in a warming climate."

Late June's record-breaking heat dome was the second to affect California that month. The first, which came a week earlier, saw temperatures reach 123 degrees in Palm Springs, a record 109 in Sacramento and 118 in the town of Thermal.

Due to climate change, the frequency of record-breaking hot temperatures continues to outpace record-breaking low temperatures by a wide and growing margin because average surface temperatures have risen by more than 1.1 degrees Celsius since the dawn of the industrial age. The impact of that shift is being felt in weather events such as this summer's unprecedented heat waves, the exceptional drought across much of the American West and the record-setting early arrival of named tropical storms, like Tropical Storm Elsa, in the Atlantic.

Last week, after the heat dome in the Pacific Northwest and British Columbia, hundreds of people died from heat-related illnesses. With temperatures poised to remain in triple digits for several days in a row, the National Weather Service is warning of potential health risks and recommending that citizens stay indoors during the heat wave.

For many migrant farmworkers, remaining indoors isn't an option. While temperatures in the Central Valley can regularly approach 100 degrees in the summer months, adding another 10 to 15 degrees can prove hazardous.

The heat dome that gripped Southern California in mid-June forced workers to endure days of 115-degree heat.

“I’d never experienced anything like that. My head hurt and I was gasping,” Luz Cruz, 18, told the Washington Post.

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