California’s power grid operator has issued a Stage 3 Emergency Alert, the highest level of warning, as a severe heatwave strains the state’s electricity supply. The alert, declared by the California Independent System Operator (ISO), triggers rotating blackouts to prevent a total system collapse. Silicon Valley, home to some of the world’s largest technology companies, is among the areas affected.
The Stage 3 alert was activated at 5:47 pm local time on Tuesday after demand surged past 50,000 megawatts, exceeding supply by nearly 3,000 megawatts. This marks the first such alert since August 2020, when similar heatwaves forced widespread outages. The ISO warned that immediate load reductions are required to avoid uncontrolled outages that could damage infrastructure.
“We are in unprecedented territory,” said ISO President Elliot Mainzer in a press conference. “We are asking all consumers to conserve energy immediately. Every kilowatt counts.”
In the tech corridor between San Francisco and San Jose, rolling blackouts have been reported, affecting major firms including Google, Apple, and Meta. Employees at several campuses were sent home early as backup generators struggled to keep critical systems online. “We are seeing a cascading effect,” said Dr. Sarah Chen, an energy analyst at Stanford University. “The heatwave is not just a local issue; it’s exposing vulnerabilities in the entire western grid.”
The heatwave, which has pushed temperatures above 110°F (43°C) in inland areas, is being described as a “heat dome” by meteorologists. The National Weather Service has extended excessive heat warnings through Friday. The combination of high temperatures, drought, and reduced hydroelectric generation has left California’s grid with little margin for error.
Governor Gavin Newsom has activated emergency operations but stopped short of declaring a state of emergency. In a statement, he urged residents to set thermostats to 78°F (25.5°C) or higher, avoid using major appliances during peak hours, and turn off unnecessary lights. “We are doing everything in our power to stabilise the grid,” he said. “But we need everyone’s cooperation.”
The California Public Utilities Commission has launched an investigation into whether energy providers failed to procure enough resources to meet demand. Critics argue that the state’s aggressive transition to renewable energy has left it vulnerable when the sun sets and solar generation drops. “California bet the farm on renewables without adequate storage,” said former Federal Energy Regulatory Commission chairman James Hoecker. “This is a predictable consequence.”
Pacific Gas & Electric (PG&E), which serves much of northern California, including Silicon Valley, reported that it had already cut power to over 50,000 customers and warned that more could follow. “We are implementing rotating outages to protect the integrity of the grid,” a PG&E spokesperson said. “We apologise for the inconvenience, but public safety is our priority.”
The outages have hit at a particularly sensitive time for the technology sector, which is already grappling with supply chain disruptions and a downturn in venture capital funding. “This is a nightmare for data centres and cloud services,” said tech analyst Michael Grant. “Any downtime translates into millions in lost revenue.”
The ISO has directed utilities to implement temporary load shedding, meaning some areas could face repeated blackouts until the heatwave subsides. The alert will remain in effect until further notice, with the ISO reassessing conditions every 12 hours.
Developing tonight: The White House has been informed. The Department of Energy is reportedly preparing to authorise emergency power transfers from neighbouring states. However, many of those states are also experiencing extreme heat. In Texas, the Electric Reliability Council of Texas (ERCOT) has issued a voluntary conservation notice, warning that it too could face shortfalls.
For now, residents and businesses in California are left in the dark, literally and figuratively. “We knew this day would come,” said Dr. Chen. “The question is whether we can adapt quickly enough.”
