Much of California remained under excessive-heat warnings Thursday, and residents of the Golden State have again been asked to limit electricity usage amid an unusual September heat wave. 

The National Weather Service said temperatures in California, particularly over interior valley regions, were expected to stretch “well into the triple digits” through Friday. Temperatures are expected to cool this weekend, with Hurricane Kay making its way toward the southern part of the state. 

Another flex alert, this time from 3 to 10 p.m., was issued by the California Independent System Operator in an effort to avoid rolling blackouts. 

California’s electric grid operator issued Level 2 energy emergency alerts across the state at 3 p.m. Thursday, urging residents to reduce energy use from 4 p.m. to 9 p.m.

Flex alerts are issued by CAISO when extreme heat causes electricity usage to increase, straining the state’s power supply, according to the operator’s website. The alerts are issued during the evening hours because that’s when people come home and turn on air conditioning, lights and appliances, the website adds.

Californians were able to avoid rolling power outages Tuesday and Wednesday during flex alerts. 

Hurricane Kay to bring rain in California

Hurricane Kay, which developed off western Mexico, is part of what will bring some relief to Southern California as it heads north.

As the hurricane continues northwest, it’s expected to dump rain on parts of the state starting Friday, according to the National Weather Service.

Some areas could get up to 6 inches of rain, potentially leading to flash flooding, the NWS said Thursday.