(KRON) — California ISO has issued an Energy Emergency Alert 1 for Tuesday that has been upgraded to an EEA 2. The alert takes effect from 4 p.m. through 9 p.m. due to excessive strain on the grid from the unprecedented September heat wave.

“Consumers are strongly urged to use less energy to avoid rotating power outages,” said the agency in a tweet.

According to the CAISO website, an EEA level 1 is issued when “real-time analysis shows all resources are in use or committed for use, and energy deficiencies are expected.” When such an alert is issued, the agency says “Market participants are encouraged to offer supplemental energy and ancillary service bids.”

“Consumers are encouraged to conserve energy,” the website goes on to state.

Emergency Energy Alerts belong to a three-tiered system. In the event of an EEA 2, “ISO requests emergency energy from all resources and has activated its emergency demand response program.” In a level 2 alert, “consumers are urged to conserve energy to help preserve grid reliability.”

An EEA 3 is issued when the “ISO is unable to meet minimum Contingency Reserve requirements and controlled power curtailments are imminent or in progress according to each utility’s emergency plan.”

In the event of an EEA 3, “maximum conversation by consumers” is requested.

Tuesday is forecast to be the worst day of the heat wave so far.

In a press release, CAISO advised consumers to be prepared for possible rotating power outages on Tuesday evening. According to the press release, “the hottest weather of this historic heat wave is forecast to push electricity demand to an all-time high.”

The ISO is expected to declare an EEA 3 around 5:30 p.m., the press release states. That would be one step away from ordering rotating power outages.

Peak demand on Monday was 49,020 megawatts. Outages were fended off by “consumer conservation, imports and emergency resources,” according to the press release.

“We’re heading into the worst part of this heat wave and the risk for outages is real and it’s immediate.”

Gov. Gavin Newsom

“We’re heading into the worst part of this heat wave and the risk for outages is real and it’s immediate,” California Gov. Gavin Newsom said in a recorded message on Twitter. “These triple-digit temperatures throughout much of our state are leading not surprisingly, to record demand on the energy grid.”

Already, many parts of the Bay Area have experienced power outages, some, like Livermore, amid record-breaking temperatures. While a slight cooldown is forecast for Wednesday, the potential for rolling blackouts is likely to remain for several days as triple-digit temps are forecast to last throughout the week.

A Flex Alert issued for Tuesday was the seventh consecutive such alert issued since the heat wave began. According to the press release, Flex Alerts, along with consumer and commercial demand response, have helped to extend sparse power supplies at critical hours so far this week by providing operators with extra cushion in supply.

For Tuesday, electricity demand is forecast at more than 52,000 megawatts, a new historic all-time high for the grid. As the state weathers what is projected to be the hottest day of the prolonged heat wave, grid conditions are expected to get worse.

Rotating power outages could be ordered in order to maintain grid stability, the release states. “If outages are initiated, consumers can expect to receive notifications from power providers on areas affected and time duration,” the release advised.