Californians are being asked to conserve energy use Tuesday afternoon if at all possible, as the threat of blackouts looms with the pending demand for power during the late-day heat.

The worst of this week's heatwave may be coming today, as even more of the state gets baked in record-breaking temperatures. State power authorities gave a press conference Monday to pat us all on the back for conserving some energy, bringing in demand at two percent below forecasts. But Californians will need to do even more to forestall blackouts today, especially around 4 and 5 p.m., when energy use is expected to peak.

"We have now entered the most intense phase of this heatwave," said Elliot Mainzer, the chief executive of the California Independent System Operator (CAISO), the state authority overseeing the power grid, per the New York Times. “We need two to three times as much conservation as we’ve been experiencing to keep the power on.”

Largely driven by air conditioner use, CAISO is predicting a 51,000 megawatt load at peak time on Tuesday, likely around 5:30 p.m. That would exceed the state's grid capacity by around 5,000 megawatts, as KPIX explains, necessitating blackouts — the likes of which we haven't seen since August and September 2020.

Back in May, CAISO tried to warn us that such blackouts could be coming, and at the time they predicted an excess demand of 1,700 megawatts, which is the equivalent to the output of one power plant.

As for the 51,000 megawatt peak, Mainzer said, "Right now our goal is to not see that number." Mainzer said the current Flex Alert and need for energy conservation "absolutely essential."

California's grid runs primarily on solar power and natural gas during the daylight hours, and as solar inputs decline after 5 p.m., the real strain occurs on super-hot days like today. The state gets some power from other states, and CAISO has asked for four new temporary emergency power generators to come online today for the first time, but their help is not nearly enough to make up the potential 5,000 megawatt shortfall.

The Department of Water Resources (DWR), installed the four natural-gas-powered emergency generators in Roseville and Yuba City last year, and this is the first time they'll be put to use. In total, the four generators can produce up to 120 megawatts of power — only enough to power about 120,000 homes.

"DWR has been planning for this moment for months and we’re proud of our role in safeguarding the statewide energy grid," said Karla Nemeth, DWR Director, in a statement per Yubanet. "We are doing everything possible to help keep the lights on and the air conditioning running so millions of Californians can stay safe and healthy during this extreme heat event."

Conservation efforts are less of an issue for San Franciscans, many of whom live without air conditioning. But Alice Reynolds, president of the California Public Utilities Commission, was encouraging people in hot, inland areas to "pre-cool" their homes in the early part of Wednesday, bringing the indoor temp down to 70 degrees, and then cranking the thermostat to 78 or higher come 4 p.m.

Also, everyone is being asked not to use large appliances between 4 and 9 p.m., and not to charge electric vehicles during that time either.

CAISO issued a Stage 2 Energy Emergency Alert between 6:30 p.m. to 8 p.m. on Monday, which is the second of three stages and the one in which backup generators are put into use. Stage 3 will involve rolling blackouts.

The state managed to avoid any blackouts in the summer of 2021, but the year prior saw similar peak energy days and several days of rolling blackouts at this time of year.

High temperatures are expected to hit triple digits across much of inland California today for the second day in a row. The highest temp recorded Monday in the region appears to have been in Livermore, where it hit 116 degrees — breaking a previous 108-degree record from 72 years ago.

Related: Get Ready for Blackouts This Summer As 'Unprecedented' Strain Could Affect CA's Power Grid