A sustained heat wave across California has prompted a statewide Flex Alert to be extended into its seventh day.
For a full week, Californians have been asked to cut down on energy use between 4 p.m. and 9 p.m.
The call comes amid strain on the state's power grid. Officials say they expect that energy shortages are expected. The shortages could cause blackouts on Tuesday.
In a message from Gov. Gavin Newsom's office, officials say conserving energy now could help avoid outages Tuesday afternoon and evening.
"Today is going to be the hottest part of the heat wave and will break demand records on the grid," the message from the governor's office said on Sept. 6.
The California Independent System operator declared an Energy Emergency Alert on Tuesday.
In the hours before 4 p.m., officials urge people to pre-cool their homes and close their windows and blinds to keep temperatures down. After 4 p.m., people are asked to turn their thermostats up to 78 degrees or above and avoid using major appliances.
Officials say the heat wave is on track to be the hottest and longest on record in California during September.
More Flex Alerts could be issued through the week.