Irene Karulis, 86, sat in her darkened, airless living room yesterday, trying to recall the maddening moment when her home in Northwest Washington lost electrical power for the second time in a matter of days.

Was it Sunday? Was it Monday?

Her 103-year-old stepmother, Berta Roze, was slumped in a chair across the room, sipping instant coffee. Karulis smiled, her hand over her chest, a reminder to take steady breaths.

"What does it matter?" she asked. "We're miserable."

Misery was the mantra across the region yesterday as temperatures soared to 97 degrees at Reagan National Airport, and children and adults took shelter anywhere they could find cool air: in homes, offices, restaurants and shopping malls.

With swelter foreseen until at least tonight, Pepco officials said a demand record was set yesterday and warned that power should be used prudently. "We're not worried about major blackouts but small outages, which we have been getting," spokesman Bob Dobkin said.

More than 17,000 homes served by three utility companies were without power at times last night. They included 5,000 in Montgomery County, 3,800 in Anne Arundel County, 2,000 in Northern Virginia and 6,900 in the District. Some of the District's problems apparently stemmed from a substation fire at 10th and L streets NW.

Dominion Virginia Power reached its highest demand on record Monday for the service area in Virginia and North Carolina. Figures for yesterday will not be available until today, but the company said it might have broken that record.

Because of the heat and air quality, the D.C. Department of Motor Vehicles shut its inspection station on Half Street SW at 1 p.m., and summer classes at Cardozo Senior High were dismissed early.

The city extended hours at public swimming pools and opened cooling centers at senior citizen facilities as well as in government buildings.

Not everyone could find relief.

Some District residents along Sixth Street in Takoma Park, where Karulis and Roze live, lacked power from about 8:45 p.m. Monday until 6 p.m. yesterday.

Some residents said it was their second blackout in a few days, the first coming with Saturday's storm.

Jaslean LaTaillade, 36, an assistant professor at the University of Maryland, lives at Sixth and Aspen streets. She said she lost power, regained it, and lost it again Monday.

Her mother, Stella, 64, was supposed to come Saturday, LaTaillade said, but stayed away because of the first outage. She arrived from New York only to learn of the second.

"Unbelievable, unbelievable," said Stella LaTaillade.

The retired nursing administrator's mood was not exactly bright after sleeping in a hot bed next to her daughter Christiane, 32, a social worker. And, she said, the lack of electricity meant no ice for a chronically aching shoulder.

After her daughter tried unsuccessfully to get service, the mother called Pepco herself. By early afternoon, no one had responded. "This is a public service people are entitled to," she said. "There is a lack of concern for customers."

Power was restored, Dobkin said, at 7:06 a. m. Saturday after the first outage, though LaTaillade insisted she was without power all that day.

The second outage on the street, Dobkin said, was reported about 8:45 p.m. Monday. He said a crew could not get to the area until yesterday at 12:52 p.m., in part because of service disruptions in other sections of the city after the storm.

"That was the first they could get people there," he said.

Karulis said losing power for a second time Monday night was especially confounding. Still, she refused a granddaughter's invitation to take shelter at her Georgetown home.

"It's difficult to change places," said the retired Voice of America announcer, who emigrated from Latvia more than 50 years ago.

She had dry Rice Krispies and berries for breakfast and sipped water. Her stepmother, she said, groused about being unable to listen to her book on tape, an anthropologist's memoir. A real cup of coffee would have helped, too.

Staff writers Aymar Jean, Clarence Williams, Martin Weil and Debbi Wilgoren contributed to this report.

Irene Karulis tries to keep cool with a washcloth as she and stepmother Berta Roze wait for power to be restored.