The sun sets behind power lines and poles in Rosemead, California (Frederic J. Brown/AFP/Getty Images)

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The coming three-day holiday heat wave will be just as hot as the one in mid-August, and Californians are forecast to use just as much energy, pushing the state’s utilities to the brink of running out of power.

But will we experience rolling outages, as happened in mid-August?

The simple answer:

The state’s power managers forecast demand and production one day ahead of time, and on Thursday they said it’s too early for them to know if rolling outages will be needed. The worst of the heat starts on Saturday, and things could change.

The more complicated answer:

Rolling outages happen if there is too much demand for power and not enough supply. So it will depend on how much we all conserve, and how much electricity the state’s combined utilities can produce or buy to meet the peak demand.

Here’s what you need to know about potential outages and your role in preventing them this long holiday weekend:


The California Independent System Operator, (CAISO), which manages much of the state’s power grid, has issued a three-day statewide Flex Alert starting on Saturday asking for power customers to conserve energy from 3 to 9 p.m. each day of the long holiday weekend.

In terms of supply, high heat across a very large region like the West could mean energy providers across multiple states are all chasing the same power, putting them in competition with each other. Some will get more, others less.

How much power is available also depends on the weather. Like a sudden cloud bank cutting solar power production, or a fall off of wind. Both will reduce supply.

Also, fires are still burning in California, and if one of them causes a transmission line to shut down, that can cut the amount of power coming in. A power plant breakdown can also stress the power grid.


Most city power utilities and Southern California Edison are part of CAISO. (LADWP along with Burbank and Glendale utilities are not, they do their own grid management.)

The members of the CAISO buy and generate power, and make it available to each other. When it looks like there might not be enough, CAISO can issue a statewide Flex Alert calling for conservation by its member utilities, as it’s done now.

If the squeeze gets worse, CAISO can also buy more power on the open market, and order the member power utilities to impose emergency measures. The most serious of those measures are rolling power outages.

In a rolling outage, a utility, say Pasadena Water and Power, would cut off electricity to one segment of its customer base for an hour or two. Then their power would be restored and another segment of the population is cut off. In this way, the utility forces its entire customer base to use less power, because a good portion of the customers simply don’t have any.

Essentially, rolling outages are a controlled way to lower overall demand for power, to keep the grid stable and avoid wider, uncontrolled outages.


Here are the steps you could expect to see:

Statewide Flex Alert: This is a request for all power consumers to reduce their use of electricity at a certain time – usually in the afternoon to evening. The Flex Alert for this weekend begins Saturday and lasts through Monday, with conservation requested for six hours each day.

If you’re in the midst of several days of Flex Alerts, the advice is to cool your house to below 78 degrees early in the day, so when it heats up outdoors later, it won’t take as much electricity and air conditioning to cool it to 78.

Here are other things to do to help the region save energy:

  • Unplug phone chargers, microwave ovens, miscellaneous appliances and electronics.
  • If you can get by with a fan instead of air conditioning, it will use less power.
  • Pool pumps can be left off for a few hours without damaging your pool. In fact, if you have a pool, you should go jump in it to cool off.

During this weekend’s Flex Alert, utilities are supposed to cancel unnecessary maintenance work that would take any generators or transmission lines out of service. They want to keep as much of the power grid working as possible.

ISO Declares Stage 2 Emergency: At this point, it will look like a mere Flex Alert is not going to result in enough energy savings to meet the demand. So it’s a warning that power outages are possible or likely.

So keep going with the power conservation – but it’s also time to prepare for getting through an hour or two of no electricity.

  • Keep your refrigerator and freezer closed.
  • Close drapes to keep the cool temperatures indoors.
  • If you have medicines that need to stay cold, bag up some ice and put it in your refrigerator with your medicine.

If your health would suffer from a few hours in a hot house or apartment, seek out a cooling center, or some public place with air conditioning where you can safely be inside without being too close to other people. Here are cooling centers in Los Angeles and in county areas.

Some indoor malls in L.A., Orange, Riverside and San Bernardino Counties are open now, but with limited numbers allowed indoors, and with food courts closed.

ISO Declares Stage 3 Emergency: When the CAISO declared a Stage 3 Emergency in August, it was the first one in 20 years. A Stage 3 means that utilities in the CAISO system will institute rolling outages, for an hour or two at a time.


Thursday evening, the governor signed an emergency proclamation intended to lift some restrictions on forms of energy production that are too polluting or uneconomical to be allowed during normal times.

So for example, companies with emergency generators or portable generators can fire them up to spare the draw that factories or big buildings might normally put on the power grid.

Big ocean tankers would be allowed to burn fuel to supply their own energy when docked at port, rather than pull from the power grid.

And some types of fuel that are generally not allowed to be burned in the L.A. Basin because they pollute the air would be allowed during the heat wave, again, to reduce the demand for power.