WASHINGTON — Millions of people in a swath of states along the East Coast and farther west went into a third sweltering day without power Monday after a round of summer storms that killed more than a dozen people.

The outages left many to contend with stifling homes and spoiled food over the weekend as temperatures approached or exceeded 100 degrees.

Around 2 million customers from North Carolina to New Jersey and as far west as Illinois were without power Monday morning. And utility officials said the power would likely be out for several more days. Since Friday, severe weather has been blamed for at least 18 deaths, most from trees falling on homes and cars.

The power outages had prompted concerns of traffic problems as commuters took to roads with darkened stoplights. But throughout northern Virginia, there was less traffic than normal in many places Monday as federal workers took advantage of liberal leave that was put in place for the day.

To alleviate traffic congestion around Baltimore and Washington, federal and state officials gave many workers the option of staying home Monday. Maryland’s governor also gave state workers wide leeway for staying out of the office.

“It was less traffic,” said D.C. resident Rob Lavender, who commuted to Arlington County from the district. “It’s more hectic on a regular day.”

There were scattered stoplight outages and some transit delays for Maryland commuters headed into Washington.

“It was a mess,” said Jason Lynch, a 23-year-old Energy Department software developer.

He counted at least three malfunctioning stoplights during his two-mile bus ride from Colesville to the Glenmont stop on Washington’s Metro subway system.

“The light coming out of my neighborhood was blinking red, and it was blinking yellow for the main direction of traffic,” he said. “People would still get confused. At the yellow light, they would stop and let people at the red light go, and the people behind them would honk at them.”

There were more than 400 signal outages in Maryland on Monday, including more than 330 in hard-hit Montgomery County outside the nation’s capital, according to the State Highway Administration. There were 100 signal outages in northern Virginia late Sunday afternoon, and 65 roads were closed, although most were secondary roads.

“If you have to drive or need to drive, leave yourself a lot of extra time,” Maryland State Highway Administration spokesman Charlie Gischlar said. “There’s going to be delays.”

Some drivers resorted to ingenuity to get to work. On a residential street in suburban Falls Church, Va., just outside Washington, downed trees blocked the road on either side. Neighbors used chain saws to cut a makeshift path on one side, but the other remained completely blocked by a massive oak tree.

“They kind of forgot about us out here,” resident Eric Nesson said.

Still, residents took the aggravation with good humor. Posted on the oak tree was a sign saying: “Free firewood you haul.” The tree lay across a smashed Ford pickup truck, with a sign reading: “For SALE. Recently lowered.”

Meanwhile, Coast Guard officials say they have suspended the search for a man who disappeared early Saturday while boating during the storm off Maryland.

On Sunday night in North Carolina, a 77-year-old man was killed when strong winds collapsed a Pitt County barn where he was parking an all-terrain vehicle, authorities said. In neighboring Beaufort County, a couple was killed when a tree fell on the golf cart they were driving. Officials said trees fell onto dozens of houses, and two hangars were destroyed at an airport in Beaufort County.

The damage was mostly blamed on straight-line winds, which are strong gusts pushed ahead of fast-moving thunderstorms like a wall of wind.

Elsewhere, at least six of the dead were killed in Virginia, including a 90-year-old woman asleep in her bed when a tree slammed into her home. Two young cousins in New Jersey were killed when a tree fell on their tent while camping. Two were killed in Maryland, one in Ohio, one in Kentucky and one in Washington.

In West Virginia, authorities said one person died early Sunday when the all-terrain vehicle they were riding hit a tree that had fallen over a road.

For survivors, it was a challenge to stay cool over the weekend.

From Atlanta to Baltimore, temperatures approached or exceeded triple digits. Atlanta set a record with a high of 105 degrees, while the temperature hit 99 at Ronald Reagan Washington National Airport just outside the nation’s capital. With no air conditioning, officials urged residents to check on their elderly relatives and neighbors. It was tough to find a free pump at gas stations that did have power, and lines of cars snaked around fast-food drive-thrus.

Power crews from as far away as Florida and Oklahoma were on their way to the mid-Atlantic region to help get the power back on and the air conditioners running again. Even if people have generators, the gas-run devices often don’t have enough power to operate an air conditioner.

And power restoration was spotty: Several people interviewed by The Associated Press said they remained without power even though the lights were on at neighbors’ homes across the street. In Maryland, Gov. O’Malley promised he would push utility companies to get electricity restored as quickly as possible.

“No one will have his boot further up Pepco’s and BGE’s backsides than I will,” O’Malley said Sunday afternoon, referring to the two main utilities serving Maryland.