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Tire pressure also drops in cold weather, Ms. Tejeda de Gomez said, and she warned that drivers should fill up their gas tanks to at least half full to avoid gas lines freezing.

For people unfortunate enough to work outside for at least part of the day, bundling up and taking frequent breaks is key.

Brian Hall, spokesman for the National Park Service, said rangers will be out to assist any tourists braving the cold.

“We are open year-round, our folks are used to working in inclement weather — not just snow, but rain as well,” he said. “We encourage folks to do what makes common sense.”

Reggie Sanders, spokesman for the D.C. Department of Transportation, said road crews will likely not be working in the elements unless a major issue arises that would put travelers at risk. In that case, employees would be switched out regularly and monitored to ensure they have adequate shelter and supplies.

“We would not want to put our employees at risk,” Mr. Sanders said. “I’ve lived here all my life and have never seen anything like it.”

The staff of the Washington Humane Society must balance the safety of its own workers and concern for four-legged clients.

Daniel D’Eramo, senior humane law enforcement officer, warned that even though dogs and cats have a body covered in fur they are just as susceptible to the cold, especially the former.

“A lot of people think that a fur coat does a lot more than it actually does,” he said. “Yes, a dog can handle being outside, but if a dog is just sitting at the back door, bring them back in. In sub-freezing temperatures, there’s no need for dogs to spend extended periods of time outside once they’ve gotten exercise.”

• This article is based in part on wire service reports