Authorities are telling Californians to conserve electricity Thursday evening, as a heat wave that coincides with a severe drought that has limited the availability of hydroelectric power to the state.

The California Independent System Operator has issued a “Flex Alert” for the hours of 5:00 p.m. to 10:00 p.m., asking residents to conserve electricity when demand is expected to be highest. High temperatures are expected throughout the region on Thursday and Friday.

Hydroelectric power generated from the state’s largest dams accounted for nearly 11% of California’s power supply in 2018. Together with hydroelectric power from smaller dams, hydroelectric power accounted for over 12% of the total. Solar and wind power accounted for just over 11% each; natural gas was the largest power source, at nearly 35%.

Last August, California suffered blackouts during a heat wave, as overcast skies and calm winds meant that renewable energy sources were unavailable to deal with surging demand from residents using air conditioning and fans to keep cool.

At the time, Governor Gavin Newsom admonished residents that California needed to “sober up” about the weaknesses of renewable energy sources, adding that the state needed “backup” and “insurance” from traditional fossil fuel sources during times of peak demand.

Despite that, as the Sacramento Bee reported Wednesday, “Gov. Gavin Newsom’s administration has refused to waver from the state’s goal of building a carbon-free power grid by 2045, as dictated by state law.”

Joel B. Pollak is Senior Editor-at-Large at Breitbart News and the host of Breitbart News Sunday on Sirius XM Patriot on Sunday evenings from 7 p.m. to 10 p.m. ET (4 p.m. to 7 p.m. PT). He is the author of the recent e-book, Neither Free nor Fair: The 2020 U.S. Presidential Election. His recent book, RED NOVEMBER, tells the story of the 2020 Democratic presidential primary from a conservative perspective. He is a winner of the 2018 Robert Novak Journalism Alumni Fellowship. Follow him on Twitter at @joelpollak.