CNN  — 

Some of the warmest places in Texas, where rolling power outages are occurring across the chilly state, are inside cars and trucks parked in the driveway of a home without electricity.

Chey Louis of Irving told CNN his family in Grand Prairie had planned a small socially distanced gathering to celebrate his younger brother’s birthday.

But instead of celebrating, they have spent the day trying to stay warm. “They have been in the car all day with the heater on,” he said. “The inside of their home has dropped below 40 degrees.”

Rolling power blackouts were ordered across Texas on Monday as a winter storm and frigid temperatures gripped the state and knocked out service to more than 4 million customers.

The rotating outages could continue until the state’s weather emergency ends, according to the Electric Reliability Council of Texas (ERCOT), a major grid operator that controls about 90% of the state’s electric load.

Gov. Gregg Abbott said in a Twitter post that the state’s power grid has not been compromised.

“The ability of some companies that generate the power has been frozen. This includes the natural gas & coal generators,” Abbott wrote, adding that ERCOT and the Public Utility Commission of Texas are working to get power back online and will give priority to residential consumers.

Frozen wind turbines and limited gas supplies have hampered the ability to generate enough power, according to a statement from ERCOT.

People in Houston, the fourth most populous city in the United States, may be in the dark into Tuesday, according to Mayor Sylvester Turner.

As of Monday afternoon, there were 1.2 million CenterPoint customers without power, including in the city of Houston and the Houston region, Turner said, a number that he said could increase as the weather gets colder in the evening.

“I just want to be very upfront with the people of the city: If you are without power right now, it is very conceivable that you could be without power throughout the rest of today and possibly even going into tomorrow,” Turner said.

Rotating blackouts occur when power companies cut off electricity to residential neighborhoods and small businesses, typically for 10 to 45 minutes before being rotated to another location, ERCOT said. Traffic lights and infrastructure may also lose power during these blackouts.

Bundling up and working from the pickup

Louis said he has been without power in his apartment in the Dallas suburb for eight hours. “The power went out early this morning,” he told CNN. “We were given no warning.” The temperature inside his apartment was 59 degrees and dropping each hour, he said.

“My lungs are tight. I need my nebulizer,” wrote Louis, who suffers from extreme asthma, in a post to social media. After hours and several calls to the power company Oncor, Louis said they stopped taking calls and told customers to prepare to be without power for an extended and unknown amount of time.

Louis said he does not feel safe traveling to find warmth. He plans to wait at his apartment until the power returns. “I’ve duct taped my doors and windows to slow the temperature drop and I’m in multiple layers of clothing, in multiple blankets using my cats for warmth,” he said. “For now it feels like a waiting game.”

Ryan Rijken said his family in north Texas has been dealing with rolling power outages since around 3 a.m. Monday. His wife, Salena, is 8 months pregnant and they also have two young boys, Max, 4, and Theo, 2.

“It has been on and off intermittently,” said Rijken, who lives about 45 miles north of Dallas in Celina. “We get about 30 min on, 45 off. Some stretches have been toward an hour either way.

“My wife is … keeping our boys bundled under blankets while they hang out during the outages. I’m currently working from my pickup and taking calls due to power outage and a lack of internet.”

In Katy, just west of Houston, Tricia Lydick said her home has been without power since 5:30 a.m. Monday with no sign of it returning anytime soon.

Lydick lives with her brother, Michael Towns, and their mother, Ann Towns, who are both disabled. Her mother has chronic obstructive pulmonary disease and requires oxygen around-the-clock. The family has extra tanks with enough to last 12 hours.

But her mother uses a CPAP machine to help her breathe while sleeping and without electricity, that is impossible for her, Lydick told CNN.

“Four hours isn’t a huge deal but I don’t want it to get to where we start running out of oxygen for Mom,” Lydick said. “We are native Texans and haven’t ever had temps like this before.”

She’s been trying to contact her power company on the phone but to no avail. The family is using blanket and jackets to keep warm in the house.

“Since all the roads are iced over, it’s way more difficult for the lines to be fixed,” she said. “I totally get that.”

If the power outages last longer than anticipated, Lydick said, her first thought would be to take her mom to the hospital.

“But the roads are iced over, so I don’t know how I could,” she said. “She can’t live without her oxygen.”

Entire state is freezing

More than 4 million customers in Texas had no power as of midday Tuesday, according to Poweroutage.us, a website that tracks power outages across the country.

Oncor, an energy company serving parts of north Texas including Dallas, tweeted Monday that the state’s power system “is currently facing an unprecedented shortfall of electric generation,” and that ERCOT “has requested Oncor & utilities across TX to implement controlled power outages to reduce high demand and protect the integrity of the electric grid.”

Oncor customers, the company said, should be prepared to be without power for an extended period of time.

“The length of these controlled outages have been significantly extended due to current emergency grid conditions & severe cold weather. These outages are taking place across the service territory & ERCOT has said they could be required through Tues,” Oncor tweeted.

Snow fell across much of Texas, including more than 10 inches in San Angelo, its snowiest day on record, and 4 inches in Dallas to tie for its seventh snowiest day on record.

The entire state was below freezing, with temperature ranging from 25 degrees in Brownsville in the south to 15 degrees below zero in the Panhandle. A trace of snow was reported in Brownsville, only the third time since 1898 that snow was reported in the city in the state’s southernmost point along the US-Mexico border.

Temperatures in the high teens were predicted for Dallas on Monday, while Houston was expecting a high temperature in the mid-20s. Below-freezing temperatures are expected in Dallas through Thursday.

The city of Houston recommended people conserve energy by turning down thermostats to 68 degrees Fahrenheit, unplugging nonessential lights and appliances, opening curtains in the day to allow sunlight and closing curtains at night to reduce heat loss.

The rolling blackouts caused several police facilities to operate on emergency generators, said Houston police Chief Art Acevedo.

“Please reduce the load on the electric grid by keeping use to a minimum,” Acevedo tweeted Monday.

The city of Galveston estimated that 90-95% of households were without power Monday because of the increased demand for electricity.

The largest oil refinery in the United States, in Port Arthur, is shutting down due to the freezing weather.

The refinery’s operator, Motiva Enterprises, said in a statement that “unprecedented freezing temperatures necessitated safely and methodically shutting down our Port Arthur Manufacturing Complex.”

‘Record-breaking electric demand’

ERCOT ordered the rolling outages around 1:30 a.m. CT (2:30 a.m. ET) Monday. ERCOT set a new winter peak demand for electricity between 6 and 7 p.m. Sunday, topping the old record from January 2018, ERCOT said in a tweet.

“We are experiencing record-breaking electric demand due to the extreme cold temperatures that have gripped Texas,” ERCOT President and CEO Bill Magness said in a news release. “At the same time, we are dealing with higher-than-normal generation outages due to frozen wind turbines and limited natural gas supplies available to generating units.”

Entergy Texas, which provides power to approximately 461,000 customers across 27 counties in the state, according to its website, said it started the rolling outages on Monday.

“We apologize for the inconvenience these outages may cause, but we have an unusual situation right now driven by extreme weather conditions. We are working to respond and restore power as soon as it is safely possible,” said Stuart Barrett, vice president of customer service.

“While our crews worked to prepare for this storm, a loss of generation combined with the peak load has caused a strain on the system. As a result, we are short of the power needed to meet our customers’ demands across southeast Texas.”

Southwest Power Pool, which manages electrical grid operations in North Texas and 16 other states, said it will have rolling blackouts.

“In our history as a grid operator, this is an unprecedented event and marks the first time SPP has ever had to call for controlled interruptions of service,” said Lanny Nickell, SPP’s executive vice president and CEO, in a news release.

SPP told transmission operators to reduce demand by the amount needed to prevent further uncontrolled outages, according to the news release.

CNN’s Jeremy Grisham, Kay Jones, Alison Kosik, Gregory Lemos, Tyler Mauldin and Artemis Moshtaghian contributed to this report.