You know how the lights seem to dim or flicker when the three vacuums, two margarita blenders and seven hair dryers are running on high? Don’t forget the air conditioner, either. That’s your house’s power supply under duress. Now, imagine more than 30 million dwellings doing that at any given time during the heat of a California summer. That’s a real buzz kill for the sweet margarita and house-cleaning mixer you were throwing. 
The California Independent System Operator (Cal ISO) step in when the state’s power grid is expected to reach a level of high demand. When blackouts (or those infamous rolling brownouts from the early 2000s) are possible in some areas, Cal ISO issues what is known as a Flex Alert, which urges everyone to conserve energy use as much as possible. A grid operator monitors the daily forecast and has the ability to notify businesses, local governments, residents and state agencies by media reports or emails. These alerts are typically regionally targeted and grid operators can shift energy resources within different regions to handle anticipated demands. If you want to be notified immediately of a Flex Alert, click here.
These requests for conservation are not just due to high energy demands, but also unplanned generator outages, transmission line overloads or limitations and adverse weather conditions like heat waves. In the last week, record highs hit multiple areas around California, including one of the hottest places on Earth—Death Valley. It was 126°F there on August 9, breaking a daily high record of 124°F set in 2001. The National Weather Service has also placed numerous excessive heat warnings in Southern California and the Southern Sierra Nevadas where wildfire risk is at a critical level. Oh yeah, and July was the hottest month ever. During a Flex Alert, Cal ISO recommends setting home thermostats to 78°F or higher, if possible, and waiting until after 7 p.m. to turn on the more demanding appliances. Following simple strategies like these typically reduce about 1,000 megawatts of power demand on the system. While one of the state’s two nuclear power plants (San Onofre Nuclear Generating Station) has been shut down since January, the Cal ISO says the this summer does not appear to be at immediate risk of any blackouts or brownouts. San Onofre typically added about 2,200 megawatts of power to the grid. What’s the take away? Since the Flex Alert program began in 2002, Californians have never outpaced energy supplies. Take a look at Today’s power supply and demand forecast here. “Power”-ful Dates:
- California suffered it’s largest blackout since World War II on June 14, 2000.
- The first statewide energy-based emergency on December 7, 2000 (energy reserves were below 3 percent at the time).
- Several hundred thousand people were hit with back-to-back days of rolling blackouts on January 17 and 18, 2001 under the direction of Cal ISO.
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