The cost of heating oil has climbed sharply since the war in Iran began, with prices up roughly 60 percent since Israel and the United States started attacking Iran on Feb. 28. About 3 percent of U.S. households use heating oil, and most of them live in the Northeast or Alaska.

Jonathan Robidoux, a Long Island resident, spent $1,200 on the fuel last winter and now faces a much higher bill. He is trying to decide whether to buy heating oil now or wait until the weather gets colder, in the hope that prices will drop.

The national average price of heating oil jumped 35 percent from $4.10 to $5.54 a gallon just a month after the war began, according to the Energy Information Administration. In New York, the average price reached $6.14 a gallon the week of Sept. 14, up from $3.70 a year earlier. More than 80 percent of U.S. heating oil is used in the Northeast.

Many Americans are heading into a much more expensive winter, said Mark Wolfe, executive director of the National Energy Assistance Directors Association. The organization urged Congress in July to offer more financial assistance to families struggling with rising energy costs.